diff --git a/io_scene_psk_psa/psa/builder.py b/io_scene_psk_psa/psa/builder.py
index dd0c8bd..95bd914 100644
--- a/io_scene_psk_psa/psa/builder.py
+++ b/io_scene_psk_psa/psa/builder.py
@@ -1,6 +1,6 @@
-from bpy.types import Bone, Action, PoseBone
+from bpy.types import Action, PoseBone
 
-from .data import *
+from .data import Psa
 from ..shared.helpers import *
 
 
@@ -23,10 +23,11 @@ class PsaBuildSequence:
 
 class PsaBuildOptions:
     def __init__(self):
+        self.armature_objects: List[Object] = []
         self.animation_data: Optional[AnimData] = None
         self.sequences: List[PsaBuildSequence] = []
         self.bone_filter_mode: str = 'ALL'
-        self.bone_collection_indices: List[int] = []
+        self.bone_collection_indices: List[Tuple[str, int]] = []
         self.sequence_name_prefix: str = ''
         self.sequence_name_suffix: str = ''
         self.scale = 1.0
@@ -34,90 +35,95 @@ class PsaBuildOptions:
         self.export_space = 'WORLD'
         self.forward_axis = 'X'
         self.up_axis = 'Z'
+        self.root_bone_name = 'ROOT'
 
 
 def _get_pose_bone_location_and_rotation(
-        pose_bone: PoseBone,
-        armature_object: Object,
+        pose_bone: Optional[PoseBone],
+        armature_object: Optional[Object],
         export_space: str,
         scale: Vector,
-        coordinate_system_transform: Matrix) -> Tuple[Vector, Quaternion]:
-    if pose_bone.parent is not None:
+        coordinate_system_transform: Matrix,
+        has_false_root_bone: bool,
+) -> Tuple[Vector, Quaternion]:
+    # TODO: my kingdom for a Rust monad.
+    is_false_root_bone = pose_bone is None and armature_object is None
+    if is_false_root_bone:
+        pose_bone_matrix = coordinate_system_transform
+    elif pose_bone.parent is not None:
         pose_bone_matrix = pose_bone.matrix
         pose_bone_parent_matrix = pose_bone.parent.matrix
         pose_bone_matrix = pose_bone_parent_matrix.inverted() @ pose_bone_matrix
     else:
-        # Get the bone's pose matrix and transform it into the export space.
-        # In the case of an 'ARMATURE' export space, this will be the inverse of armature object's world matrix.
-        # Otherwise, it will be the identity matrix.
-        # TODO: taking the pose bone matrix puts this in armature space.
-        pose_bone_matrix = Matrix.Identity(4)
-        match export_space:
-            case 'ARMATURE':
-                pose_bone_matrix = pose_bone.matrix
-            case 'WORLD':
-                pose_bone_matrix = armature_object.matrix_world @ pose_bone.matrix
-            case 'ROOT':
-                pose_bone_matrix = Matrix.Identity(4)
+        # Root bone
+        if has_false_root_bone:
+            pose_bone_matrix = armature_object.matrix_world @ pose_bone.matrix
+        else:
+            # Get the bone's pose matrix and transform it into the export space.
+            # In the case of an 'ARMATURE' export space, this will be the inverse of armature object's world matrix.
+            # Otherwise, it will be the identity matrix.
+            # TODO: taking the pose bone matrix puts this in armature space.
+            match export_space:
+                case 'ARMATURE':
+                    pose_bone_matrix = pose_bone.matrix
+                case 'WORLD':
+                    pose_bone_matrix = armature_object.matrix_world @ pose_bone.matrix
+                case 'ROOT':
+                    pose_bone_matrix = Matrix.Identity(4)
+                case _:
+                    assert False, f'Invalid export space: {export_space}'
 
-        # The root bone is the only bone that should be transformed by the coordinate system transform, since all
-        # other bones are relative to their parent bones.
-        pose_bone_matrix = coordinate_system_transform @ pose_bone_matrix
+            # The root bone is the only bone that should be transformed by the coordinate system transform, since all
+            # other bones are relative to their parent bones.
+            pose_bone_matrix = coordinate_system_transform @ pose_bone_matrix
 
     location = pose_bone_matrix.to_translation()
     rotation = pose_bone_matrix.to_quaternion().normalized()
 
-    location *= scale
+    # TODO: this has gotten way more complicated than it needs to be.
+    # TODO: don't apply scale to the root bone of armatures if we have a false root:
+    if not has_false_root_bone or (pose_bone is None or pose_bone.parent is not None):
+        location *= scale
 
-    if pose_bone.parent is not None:
+    if has_false_root_bone:
+        is_child_bone = not is_false_root_bone
+    else:
+        is_child_bone = pose_bone.parent is not None
+
+    if is_child_bone is not None:
         rotation.conjugate()
 
     return location, rotation
 
 
 def build_psa(context: bpy.types.Context, options: PsaBuildOptions) -> Psa:
-    active_object = context.view_layer.objects.active
-
     psa = Psa()
 
-    armature_object = active_object
-    evaluated_armature_object = armature_object.evaluated_get(context.evaluated_depsgraph_get())
-
-    armature_data = typing.cast(Armature, armature_object.data)
-    bones: List[Bone] = list(iter(armature_data.bones))
-
-    # The order of the armature bones and the pose bones is not guaranteed to be the same.
-    # As a result, we need to reconstruct the list of pose bones in the same order as the
-    # armature bones.
-    bone_names = [x.name for x in bones]
-
-    # Get a list of all the bone indices and instigator bones for the bone filter settings.
-    export_bone_names = get_export_bone_names(armature_object, options.bone_filter_mode, options.bone_collection_indices)
-    bone_indices = [bone_names.index(x) for x in export_bone_names]
-
-    # Make the bone lists contain only the bones that are going to be exported.
-    bones = [bones[bone_index] for bone_index in bone_indices]
-
-    # No bones are going to be exported.
-    if len(bones) == 0:
-        raise RuntimeError('No bones available for export')
-
-    # The bone building code should be shared between the PSK and PSA exporters, since they both need to build a nearly identical bone list.
-
-    # TODO: The PSA bones are just here to validate the hierarchy. The pose information is not used by the engine.
-    # Build list of PSA bones.
-    psa.bones = convert_blender_bones_to_psx_bones(
-        bones=bones,
-        bone_class=Psa.Bone,
+    psx_bone_create_result = create_psx_bones(
+        armature_objects=options.armature_objects,
         export_space=options.export_space,
-        armature_object_matrix_world=armature_object.matrix_world,  # evaluated_armature_object.matrix_world,
-        scale=options.scale,
+        root_bone_name=options.root_bone_name,
         forward_axis=options.forward_axis,
-        up_axis=options.up_axis
+        up_axis=options.up_axis,
+        scale=options.scale,
+        bone_filter_mode=options.bone_filter_mode,
+        bone_collection_indices=options.bone_collection_indices,
     )
 
+    # TODO: technically wrong, might not necessarily be true (i.e., if the armature object has no contributing bones).
+    has_false_root_bone = len(options.armature_objects) > 1
+
+    # Build list of PSA bones.
+    # Note that the PSA bones are just here to validate the hierarchy. The bind pose information is not used by the
+    # engine.
+    psa.bones = [psx_bone for psx_bone, _ in psx_bone_create_result.bones]
+
+    # No bones are going to be exported.
+    if len(psa.bones) == 0:
+        raise RuntimeError('No bones available for export')
+
     # We invert the export space matrix so that we neutralize the transform of the armature object.
-    export_space_matrix_inverse = get_export_space_matrix(options.export_space, armature_object)
+    # export_space_matrix_inverse = get_export_space_matrix(options.export_space, armature_object)
 
     # Add prefixes and suffices to the names of the export sequences and strip whitespace.
     for export_sequence in options.sequences:
@@ -126,6 +132,7 @@ def build_psa(context: bpy.types.Context, options: PsaBuildOptions) -> Psa:
 
     # Save the current action and frame so that we can restore the state once we are done.
     saved_frame_current = context.scene.frame_current
+
     saved_action = options.animation_data.action
 
     # Now build the PSA sequences.
@@ -137,16 +144,6 @@ def build_psa(context: bpy.types.Context, options: PsaBuildOptions) -> Psa:
     coordinate_system_transform = get_coordinate_system_transform(options.forward_axis, options.up_axis)
 
     for export_sequence_index, export_sequence in enumerate(options.sequences):
-        # Look up the pose bones for the bones that are going to be exported.
-        pose_bones = [(bone_names.index(bone.name), bone) for bone in armature_object.pose.bones]
-        pose_bones.sort(key=lambda x: x[0])
-        pose_bones = [x[1] for x in pose_bones]
-        pose_bones = [pose_bones[bone_index] for bone_index in bone_indices]
-
-        # Link the action to the animation data and update view layer.
-        export_sequence.anim_data.action = export_sequence.nla_state.action
-        context.view_layer.update()
-
         frame_start = export_sequence.nla_state.frame_start
         frame_end = export_sequence.nla_state.frame_end
 
@@ -160,26 +157,34 @@ def build_psa(context: bpy.types.Context, options: PsaBuildOptions) -> Psa:
         except ZeroDivisionError:
             frame_step = 0.0
 
-        sequence_duration = frame_count_raw / export_sequence.fps
-
         # If this is a reverse sequence, we need to reverse the frame step.
         if frame_start > frame_end:
             frame_step = -frame_step
 
+        sequence_duration = frame_count_raw / export_sequence.fps
+
         psa_sequence = Psa.Sequence()
         try:
             psa_sequence.name = bytes(export_sequence.name, encoding='windows-1252')
         except UnicodeEncodeError:
-            raise RuntimeError(f'Sequence name "{export_sequence.name}" contains characters that cannot be encoded in the Windows-1252 codepage')
+            raise RuntimeError(
+                f'Sequence name "{export_sequence.name}" contains characters that cannot be encoded in the Windows-1252 codepage')
         psa_sequence.frame_count = frame_count
         psa_sequence.frame_start_index = frame_start_index
         psa_sequence.fps = frame_count / sequence_duration
-        psa_sequence.bone_count = len(pose_bones)
+        psa_sequence.bone_count = len(psa.bones)
         psa_sequence.track_time = frame_count
         psa_sequence.key_reduction = 1.0
 
         frame = float(frame_start)
 
+        # Link the action to the animation data and update view layer.
+        for armature_object in options.armature_objects:
+            # TODO: change this to assign it to each armature object's animation data.
+            armature_object.animation_data.action = export_sequence.nla_state.action
+
+        context.view_layer.update()
+
         def add_key(location: Vector, rotation: Quaternion):
             key = Psa.Key()
             key.location.x = location.x
@@ -192,12 +197,40 @@ def build_psa(context: bpy.types.Context, options: PsaBuildOptions) -> Psa:
             key.time = 1.0 / psa_sequence.fps
             psa.keys.append(key)
 
-        # TODO: In _get_pose_bone_location_and_rotation, we need to factor in the evaluated armature object's scale.
-        #  Then also, if we're in ARMATURE export space, invert the pose bone matrix so that it's the identity matrix.
+        class PsaExportBone:
+            def __init__(self, pose_bone: Optional[PoseBone], armature_object: Optional[Object], scale: Vector):
+                self.pose_bone = pose_bone
+                self.armature_object = armature_object
+                self.scale = scale
 
-        # TODO: extract the scale out of the evaluated_armature_object.matrix_world.
-        _, _, scale = evaluated_armature_object.matrix_world.decompose()
-        scale *= options.scale
+        armature_scales: Dict[Object, Vector] = {}
+
+        # Extract the scale from the world matrix of the evaluated armature object.
+        for armature_object in options.armature_objects:
+            evaluated_armature_object = armature_object.evaluated_get(context.evaluated_depsgraph_get())
+            _, _, scale = evaluated_armature_object.matrix_world.decompose()
+            scale *= options.scale
+            armature_scales[armature_object] = scale
+
+        # Create a list of export pose bones, in the same order as the bones as they appear in the armature.
+        # The object contains the pose bone, the armature object, and a pre-calculated scaling value to apply to the
+        # locations.
+        export_bones: List[PsaExportBone] = []
+
+        for psx_bone, armature_object in psx_bone_create_result.bones:
+            print(psx_bone, armature_object)
+            # TODO: look up the pose bone from the name in the PSX bone.
+            if armature_object is None:
+                export_bones.append(PsaExportBone(None, None, Vector((1.0, 1.0, 1.0))))
+                continue
+
+            # TODO: we need to look up the pose bones using the name.
+            pose_bone = armature_object.pose.bones[psx_bone.name.decode('windows-1252')]
+
+            export_bones.append(PsaExportBone(pose_bone, armature_object, armature_scales[armature_object]))
+
+        for export_bone in export_bones:
+            print(export_bone.pose_bone, export_bone.armature_object, export_bone.scale)
 
         match options.sampling_mode:
             case 'INTERPOLATED':
@@ -221,13 +254,14 @@ def build_psa(context: bpy.types.Context, options: PsaBuildOptions) -> Psa:
                         else:
                             last_frame_bone_poses.clear()
                             context.scene.frame_set(frame=last_frame)
-                            for pose_bone in pose_bones:
+                            for export_bone in export_bones:
                                 location, rotation = _get_pose_bone_location_and_rotation(
-                                    pose_bone,
-                                    armature_object,
+                                    export_bone.pose_bone,
+                                    export_bone.armature_object,
                                     options.export_space,
-                                    scale,
-                                    coordinate_system_transform=coordinate_system_transform
+                                    export_bone.scale,
+                                    coordinate_system_transform=coordinate_system_transform,
+                                    has_false_root_bone=has_false_root_bone,
                                 )
                                 last_frame_bone_poses.append((location, rotation))
 
@@ -236,26 +270,27 @@ def build_psa(context: bpy.types.Context, options: PsaBuildOptions) -> Psa:
 
                     # If this is not a subframe, just use the last frame's bone poses.
                     if frame % 1.0 == 0:
-                        for i in range(len(pose_bones)):
+                        for i in range(len(export_bones)):
                             add_key(*last_frame_bone_poses[i])
                     else:
                         # Otherwise, this is a subframe, so we need to interpolate the pose between the next frame and the last frame.
                         if next_frame is None:
                             next_frame = last_frame + 1
                             context.scene.frame_set(frame=next_frame)
-                            for pose_bone in pose_bones:
+                            for export_bone in export_bones:
                                 location, rotation = _get_pose_bone_location_and_rotation(
-                                    pose_bone,
-                                    armature_object,
-                                    options.export_space,
-                                    scale,
-                                    coordinate_system_transform=coordinate_system_transform
+                                    pose_bone=export_bone.pose_bone,
+                                    armature_object=export_bone.armature_object,
+                                    export_space=options.export_space,
+                                    scale=export_bone.scale,
+                                    coordinate_system_transform=coordinate_system_transform,
+                                    has_false_root_bone=has_false_root_bone,
                                 )
                                 next_frame_bone_poses.append((location, rotation))
 
                         factor = frame % 1.0
 
-                        for i in range(len(pose_bones)):
+                        for i in range(len(export_bones)):
                             last_location, last_rotation = last_frame_bone_poses[i]
                             next_location, next_rotation = next_frame_bone_poses[i]
 
@@ -269,13 +304,14 @@ def build_psa(context: bpy.types.Context, options: PsaBuildOptions) -> Psa:
                 for _ in range(frame_count):
                     context.scene.frame_set(frame=int(frame), subframe=frame % 1.0)
 
-                    for pose_bone in pose_bones:
+                    for export_bone in export_bones:
                         location, rotation = _get_pose_bone_location_and_rotation(
-                            pose_bone,
-                            armature_object,
-                            options.export_space,
-                            scale,
-                            coordinate_system_transform=coordinate_system_transform
+                            pose_bone=export_bone.pose_bone,
+                            armature_object=export_bone.armature_object,
+                            export_space=options.export_space,
+                            scale=export_bone.scale,
+                            coordinate_system_transform=coordinate_system_transform,
+                            has_false_root_bone=has_false_root_bone,
                         )
                         add_key(location, rotation)
 
@@ -288,7 +324,9 @@ def build_psa(context: bpy.types.Context, options: PsaBuildOptions) -> Psa:
         context.window_manager.progress_update(export_sequence_index)
 
     # Restore the previous action & frame.
+    # TODO: store each armature object's previous action
     options.animation_data.action = saved_action
+
     context.scene.frame_set(saved_frame_current)
 
     context.window_manager.progress_end()
diff --git a/io_scene_psk_psa/psa/data.py b/io_scene_psk_psa/psa/data.py
index b881ae6..5dd82cc 100644
--- a/io_scene_psk_psa/psa/data.py
+++ b/io_scene_psk_psa/psa/data.py
@@ -11,16 +11,6 @@ Use the PsaReader::get_sequence_keys to get the keys for a sequence.
 
 
 class Psa:
-    class Bone(Structure):
-        _fields_ = [
-            ('name', c_char * 64),
-            ('flags', c_int32),
-            ('children_count', c_int32),
-            ('parent_index', c_int32),
-            ('rotation', Quaternion),
-            ('location', Vector3),
-            ('padding', c_char * 16)
-        ]
 
     class Sequence(Structure):
         _fields_ = [
@@ -59,6 +49,6 @@ class Psa:
             return repr((self.location, self.rotation, self.time))
 
     def __init__(self):
-        self.bones: List[Psa.Bone] = []
+        self.bones: List[PsxBone] = []
         self.sequences: typing.OrderedDict[str, Psa.Sequence] = OrderedDict()
         self.keys: List[Psa.Key] = []
diff --git a/io_scene_psk_psa/psa/export/operators.py b/io_scene_psk_psa/psa/export/operators.py
index b621816..aa0b61a 100644
--- a/io_scene_psk_psa/psa/export/operators.py
+++ b/io_scene_psk_psa/psa/export/operators.py
@@ -3,9 +3,8 @@ from typing import List, Iterable, Dict, Tuple, Optional
 
 import bpy
 from bpy.props import StringProperty
-from bpy.types import Context, Action, Object, AnimData, TimelineMarker
+from bpy.types import Context, Action, Object, AnimData, TimelineMarker, Operator
 from bpy_extras.io_utils import ExportHelper
-from bpy_types import Operator
 
 from .properties import PSA_PG_export, PSA_PG_export_action_list_item, filter_sequences, \
     get_sequences_from_name_and_frame_range
@@ -63,7 +62,7 @@ def is_action_for_object(obj: Object, action: Action):
     return any(obj in slot.users() for slot in action.slots)
 
 
-def update_actions_and_timeline_markers(context: Context):
+def update_actions_and_timeline_markers(context: Context, armature_objects: Iterable[Object]):
     pg = getattr(context.scene, 'psa_export')
 
     # Clear actions and markers.
@@ -72,6 +71,7 @@ def update_actions_and_timeline_markers(context: Context):
     pg.active_action_list.clear()
 
     # Get animation data.
+    # TODO: Not sure how to handle this with multiple armatures.
     animation_data_object = get_animation_data_object(context)
     animation_data = animation_data_object.animation_data if animation_data_object else None
 
@@ -80,7 +80,8 @@ def update_actions_and_timeline_markers(context: Context):
 
     # Populate actions list.
     for action in bpy.data.actions:
-        if not is_action_for_object(context.active_object, action):
+        if not any(map(lambda armature_object: is_action_for_object(armature_object, action), armature_objects)):
+            # This action is not applicable to any of the selected armatures.
             continue
 
         for (name, frame_start, frame_end) in get_sequences_from_action(action):
@@ -170,7 +171,7 @@ def get_animation_data_object(context: Context) -> Object:
     active_object = context.view_layer.objects.active
 
     if active_object.type != 'ARMATURE':
-        raise RuntimeError('Selected object must be an Armature')
+        raise RuntimeError('Active object must be an Armature')
 
     if pg.sequence_source != 'ACTIONS' and pg.should_override_animation_data:
         animation_data_object = pg.animation_data_override
@@ -275,7 +276,7 @@ class PSA_OT_export(Operator, ExportHelper):
 
     def __init__(self, *args, **kwargs):
         super().__init__(*args, **kwargs)
-        self.armature_object = None
+        self.armature_objects: List[Object] = []
 
     @classmethod
     def poll(cls, context):
@@ -380,6 +381,14 @@ class PSA_OT_export(Operator, ExportHelper):
                 bones_panel.template_list('PSX_UL_bone_collection_list', '', pg, 'bone_collection_list', pg, 'bone_collection_list_index',
                                      rows=rows)
 
+            bones_advanced_header, bones_advanced_panel = layout.panel('Advanced', default_closed=False)
+            bones_advanced_header.label(text='Advanced')
+            if bones_advanced_panel:
+                flow = bones_advanced_panel.grid_flow()
+                flow.use_property_split = True
+                flow.use_property_decorate = False
+                flow.prop(pg, 'root_bone_name', text='Root Bone Name')
+
         # TRANSFORM
         transform_header, transform_panel = layout.panel('Advanced', default_closed=False)
         transform_header.label(text='Transform')
@@ -401,18 +410,10 @@ class PSA_OT_export(Operator, ExportHelper):
         if context.view_layer.objects.active.type != 'ARMATURE':
             raise RuntimeError('The active object must be an armature')
 
-        # If we have multiple armatures selected, make sure that they all use the same underlying armature data.
-        armature_objects = [obj for obj in context.selected_objects if obj.type == 'ARMATURE']
-
-        for obj in armature_objects:
-            if obj.data != context.view_layer.objects.active.data:
-                raise RuntimeError(f'All selected armatures must use the same armature data block.\n\n'
-                                   f'\The armature data block for "{obj.name}\" (\'{obj.data.name}\') does not match '
-                                   f'the active armature data block (\'{context.view_layer.objects.active.name}\')')
-
         if context.scene.is_nla_tweakmode:
             raise RuntimeError('Cannot export PSA while in NLA tweak mode')
 
+
     def invoke(self, context, _event):
         try:
             self._check_context(context)
@@ -421,16 +422,16 @@ class PSA_OT_export(Operator, ExportHelper):
 
         pg: PSA_PG_export = getattr(context.scene, 'psa_export')
 
-        self.armature_object = context.view_layer.objects.active
+        self.armature_objects = [x for x in context.view_layer.objects.selected if x.type == 'ARMATURE']
 
-        if self.armature_object.animation_data is None:
+        for armature_object in self.armature_objects:
             # This is required otherwise the action list will be empty if the armature has never had its animation
             # data created before (i.e. if no action was ever assigned to it).
-            self.armature_object.animation_data_create()
+            if armature_object.animation_data is None:
+                armature_object.animation_data_create()
 
-        update_actions_and_timeline_markers(context)
-
-        populate_bone_collection_list(self.armature_object, pg.bone_collection_list)
+        update_actions_and_timeline_markers(context, self.armature_objects)
+        populate_bone_collection_list(self.armature_objects, pg.bone_collection_list)
 
         context.window_manager.fileselect_add(self)
 
@@ -442,9 +443,11 @@ class PSA_OT_export(Operator, ExportHelper):
         # Ensure that we actually have items that we are going to be exporting.
         if pg.sequence_source == 'ACTIONS' and len(pg.action_list) == 0:
             raise RuntimeError('No actions were selected for export')
-        elif pg.sequence_source == 'TIMELINE_MARKERS' and len(pg.marker_list) == 0:
+
+        if pg.sequence_source == 'TIMELINE_MARKERS' and len(pg.marker_list) == 0:
             raise RuntimeError('No timeline markers were selected for export')
-        elif pg.sequence_source == 'NLA_TRACK_STRIPS' and len(pg.nla_strip_list) == 0:
+
+        if pg.sequence_source == 'NLA_TRACK_STRIPS' and len(pg.nla_strip_list) == 0:
             raise RuntimeError('No NLA track strips were selected for export')
 
         # Populate the export sequence list.
@@ -511,6 +514,7 @@ class PSA_OT_export(Operator, ExportHelper):
             return {'CANCELLED'}
 
         options = PsaBuildOptions()
+        options.armature_objects = self.armature_objects
         options.animation_data = animation_data
         options.sequences = export_sequences
         options.bone_filter_mode = pg.bone_filter_mode
@@ -522,6 +526,7 @@ class PSA_OT_export(Operator, ExportHelper):
         options.export_space = pg.export_space
         options.forward_axis = pg.forward_axis
         options.up_axis = pg.up_axis
+        options.root_bone_name = pg.root_bone_name
 
         try:
             psa = build_psa(context, options)
diff --git a/io_scene_psk_psa/psa/export/properties.py b/io_scene_psk_psa/psa/export/properties.py
index 340cda2..b454240 100644
--- a/io_scene_psk_psa/psa/export/properties.py
+++ b/io_scene_psk_psa/psa/export/properties.py
@@ -217,6 +217,11 @@ class PSA_PG_export(PropertyGroup, ForwardUpAxisMixin, ExportSpaceMixin):
         ),
         default='INTERPOLATED'
     )
+    root_bone_name: StringProperty(
+        name='Root Bone Name',
+        description='The name of the generated root bone when exporting multiple armatures',
+        default='ROOT',
+    )
 
 
 def filter_sequences(pg: PSA_PG_export, sequences) -> List[int]:
diff --git a/io_scene_psk_psa/psa/importer.py b/io_scene_psk_psa/psa/importer.py
index a4c7015..4855708 100644
--- a/io_scene_psk_psa/psa/importer.py
+++ b/io_scene_psk_psa/psa/importer.py
@@ -7,8 +7,8 @@ from bpy.types import FCurve, Object, Context
 from mathutils import Vector, Quaternion
 
 from .config import PsaConfig, REMOVE_TRACK_LOCATION, REMOVE_TRACK_ROTATION
-from .data import Psa
 from .reader import PsaReader
+from ..shared.data import PsxBone
 
 
 class PsaImportOptions(object):
@@ -45,8 +45,8 @@ class PsaImportOptions(object):
 
 
 class ImportBone(object):
-    def __init__(self, psa_bone: Psa.Bone):
-        self.psa_bone: Psa.Bone = psa_bone
+    def __init__(self, psa_bone: PsxBone):
+        self.psa_bone: PsxBone = psa_bone
         self.parent: Optional[ImportBone] = None
         self.armature_bone = None
         self.pose_bone = None
diff --git a/io_scene_psk_psa/psa/reader.py b/io_scene_psk_psa/psa/reader.py
index 70cf212..c5ccf89 100644
--- a/io_scene_psk_psa/psa/reader.py
+++ b/io_scene_psk_psa/psa/reader.py
@@ -1,8 +1,9 @@
-import ctypes
+from ctypes import sizeof
+from typing import List
 
 import numpy as np
 
-from .data import *
+from .data import Psa, Section, PsxBone
 
 
 def _try_fix_cue4parse_issue_103(sequences) -> bool:
@@ -101,11 +102,11 @@ class PsaReader(object):
         psa = Psa()
         while fp.read(1):
             fp.seek(-1, 1)
-            section = Section.from_buffer_copy(fp.read(ctypes.sizeof(Section)))
+            section = Section.from_buffer_copy(fp.read(sizeof(Section)))
             if section.name == b'ANIMHEAD':
                 pass
             elif section.name == b'BONENAMES':
-                PsaReader._read_types(fp, Psa.Bone, section, psa.bones)
+                PsaReader._read_types(fp, PsxBone, section, psa.bones)
             elif section.name == b'ANIMINFO':
                 sequences = []
                 PsaReader._read_types(fp, Psa.Sequence, section, sequences)
diff --git a/io_scene_psk_psa/psa/writer.py b/io_scene_psk_psa/psa/writer.py
index a451108..05001cb 100644
--- a/io_scene_psk_psa/psa/writer.py
+++ b/io_scene_psk_psa/psa/writer.py
@@ -2,7 +2,7 @@ from ctypes import Structure, sizeof
 from typing import Type
 
 from .data import Psa
-from ..shared.data import Section
+from ..shared.data import Section, PsxBone
 
 
 def write_section(fp, name: bytes, data_type: Type[Structure] = None, data: list = None):
@@ -20,6 +20,6 @@ def write_section(fp, name: bytes, data_type: Type[Structure] = None, data: list
 def write_psa(psa: Psa, path: str):
     with open(path, 'wb') as fp:
         write_section(fp, b'ANIMHEAD')
-        write_section(fp, b'BONENAMES', Psa.Bone, psa.bones)
+        write_section(fp, b'BONENAMES', PsxBone, psa.bones)
         write_section(fp, b'ANIMINFO', Psa.Sequence, list(psa.sequences.values()))
         write_section(fp, b'ANIMKEYS', Psa.Key, psa.keys)
diff --git a/io_scene_psk_psa/psk/builder.py b/io_scene_psk_psa/psk/builder.py
index 57aa3a4..4224d85 100644
--- a/io_scene_psk_psa/psk/builder.py
+++ b/io_scene_psk_psa/psk/builder.py
@@ -1,22 +1,23 @@
 import typing
-from collections import Counter
-from typing import Dict, Generator, Set, Iterable, Optional, cast
+from typing import Dict, Generator, Set, Iterable, Optional, cast, Tuple
 
 import bmesh
 import bpy
 import numpy as np
-from bpy.types import Material, Collection, Context, Object, Armature, Bone
+from bpy.types import Collection, Context, Object, Armature
+from mathutils import Matrix
 
 from .data import *
+from .export.operators import get_materials_for_mesh_objects
 from .properties import triangle_type_and_bit_flags_to_poly_flags
 from ..shared.dfs import dfs_collection_objects, dfs_view_layer_objects, DfsObject
-from ..shared.helpers import get_coordinate_system_transform, convert_string_to_cp1252_bytes, \
-    get_export_bone_names, convert_blender_bones_to_psx_bones
+from ..shared.helpers import convert_string_to_cp1252_bytes, \
+    create_psx_bones, get_coordinate_system_transform
 
 
 class PskInputObjects(object):
     def __init__(self):
-        self.mesh_objects: List[DfsObject] = []
+        self.mesh_dfs_objects: List[DfsObject] = []
         self.armature_objects: Set[Object] = set()
 
 
@@ -25,7 +26,8 @@ class PskBuildOptions(object):
         self.bone_filter_mode = 'ALL'
         self.bone_collection_indices: List[Tuple[str, int]] = []
         self.object_eval_state = 'EVALUATED'
-        self.materials: List[Material] = []
+        self.material_order_mode = 'AUTOMATIC'
+        self.material_name_list: List[str] = []
         self.scale = 1.0
         self.export_space = 'WORLD'
         self.forward_axis = 'X'
@@ -63,14 +65,14 @@ def get_armatures_for_mesh_objects(mesh_objects: Iterable[Object]) -> Generator[
         yield modifiers[0].object
 
 
-def _get_psk_input_objects(mesh_objects: Iterable[DfsObject]) -> PskInputObjects:
-    mesh_objects = list(mesh_objects)
-    if len(mesh_objects) == 0:
+def _get_psk_input_objects(mesh_dfs_objects: Iterable[DfsObject]) -> PskInputObjects:
+    mesh_dfs_objects = list(mesh_dfs_objects)
+    if len(mesh_dfs_objects) == 0:
         raise RuntimeError('At least one mesh must be selected')
 
     input_objects = PskInputObjects()
-    input_objects.mesh_objects = mesh_objects
-    input_objects.armature_objects |= set(get_armatures_for_mesh_objects(map(lambda x: x.obj, mesh_objects)))
+    input_objects.mesh_dfs_objects = mesh_dfs_objects
+    input_objects.armature_objects |= set(get_armatures_for_mesh_objects(map(lambda x: x.obj, mesh_dfs_objects)))
 
     return input_objects
 
@@ -133,98 +135,39 @@ def _get_material_name_indices(obj: Object, material_names: List[str]) -> Iterab
                 yield 0
 
 
-def build_psk(context, input_objects: PskInputObjects, options: PskBuildOptions) -> PskBuildResult:
+def build_psk(context: Context, input_objects: PskInputObjects, options: PskBuildOptions) -> PskBuildResult:
     armature_objects = list(input_objects.armature_objects)
 
     result = PskBuildResult()
     psk = Psk()
-    bones: List[Bone] = []
 
-    if options.export_space != 'WORLD' and len(armature_objects) > 1:
-        raise RuntimeError('When exporting multiple armatures, the Export Space must be World')
+    psx_bone_create_result = create_psx_bones(
+        armature_objects=armature_objects,
+        export_space=options.export_space,
+        forward_axis=options.forward_axis,
+        up_axis=options.up_axis,
+        scale=options.scale,
+        root_bone_name=options.root_bone_name,
+        bone_filter_mode=options.bone_filter_mode,
+        bone_collection_indices=options.bone_collection_indices
+    )
 
-    coordinate_system_matrix = get_coordinate_system_transform(options.forward_axis, options.up_axis)
-    coordinate_system_default_rotation = coordinate_system_matrix.to_quaternion()
-
-    scale_matrix = Matrix.Scale(options.scale, 4)
-
-    total_bone_count = sum(len(armature_object.data.bones) for armature_object in armature_objects)
-
-    # Store the index of the root bone for each armature object.
-    # We will need this later to correctly assign vertex weights.
-    armature_object_root_bone_indices = dict()
-
-    # Store the bone names to be exported for each armature object.
-    armature_object_bone_names: Dict[Object, List[str]] = dict()
-    for armature_object in  armature_objects:
-        bone_collection_indices = [x[1] for x in options.bone_collection_indices if x[0] == armature_object.name]
-        bone_names = get_export_bone_names(armature_object, options.bone_filter_mode, bone_collection_indices)
-        armature_object_bone_names[armature_object] = bone_names
-
-    if len(armature_objects) == 0 or total_bone_count == 0:
-        # If the mesh has no armature object or no bones, simply assign it a dummy bone at the root to satisfy the
-        # requirement that a PSK file must have at least one bone.
-        psk_bone = Psk.Bone()
-        psk_bone.name = convert_string_to_cp1252_bytes(options.root_bone_name)
-        psk_bone.flags = 0
-        psk_bone.children_count = 0
-        psk_bone.parent_index = 0
-        psk_bone.location = Vector3.zero()
-        psk_bone.rotation = Quaternion.from_bpy_quaternion(coordinate_system_default_rotation)
-        psk.bones.append(psk_bone)
-
-        armature_object_root_bone_indices[None] = 0
-    else:
-        # If we have multiple armature objects, create a root bone at the world origin.
-        if len(armature_objects) > 1:
-            psk_bone = Psk.Bone()
-            psk_bone.name = convert_string_to_cp1252_bytes(options.root_bone_name)
-            psk_bone.flags = 0
-            psk_bone.children_count = total_bone_count
-            psk_bone.parent_index = 0
-            psk_bone.location = Vector3.zero()
-            psk_bone.rotation = Quaternion.from_bpy_quaternion(coordinate_system_default_rotation)
-            psk.bones.append(psk_bone)
-
-            armature_object_root_bone_indices[None] = 0
-
-        root_bone = psk.bones[0] if len(psk.bones) > 0 else None
-
-        for armature_object in armature_objects:
-            bone_names = armature_object_bone_names[armature_object]
-            armature_data = typing.cast(Armature, armature_object.data)
-            bones = [armature_data.bones[bone_name] for bone_name in bone_names]
-
-            psk_bones = convert_blender_bones_to_psx_bones(
-                bones=bones,
-                bone_class=Psk.Bone,
-                export_space=options.export_space,
-                armature_object_matrix_world=armature_object.matrix_world,
-                scale=options.scale,
-                forward_axis=options.forward_axis,
-                up_axis=options.up_axis,
-                root_bone=root_bone,
-            )
-
-            # If we are appending these bones to an existing list of bones, we need to adjust the parent indices.
-            if len(psk.bones) > 0:
-                parent_index_offset = len(psk.bones)
-                for bone in psk_bones[1:]:
-                    bone.parent_index += parent_index_offset
-
-            armature_object_root_bone_indices[armature_object] = len(psk.bones)
-
-            psk.bones.extend(psk_bones)
-
-    # Check if there are bone name conflicts between armatures.
-    bone_name_counts = Counter(x.name.decode('windows-1252').upper() for x in psk.bones)
-
-    for bone_name, count in bone_name_counts.items():
-        if count > 1:
-            raise RuntimeError(f'Found {count} bones with the name "{bone_name}". Bone names must be unique when compared case-insensitively.')
+    psk.bones = [psx_bone for psx_bone, _ in psx_bone_create_result.bones]
 
     # Materials
-    for material in options.materials:
+    match options.material_order_mode:
+        case 'AUTOMATIC':
+            mesh_objects = [dfs_object.obj for dfs_object in input_objects.mesh_dfs_objects]
+            materials = list(get_materials_for_mesh_objects(context.evaluated_depsgraph_get(), mesh_objects))
+        case 'MANUAL':
+            # The material name list may contain materials that are not on the mesh objects.
+            # Therefore, we can take the material_name_list as gospel and simply use it as a lookup table.
+            # If a look-up fails, replace it with an empty material.
+            materials = [bpy.data.materials.get(x.material_name, None) for x in options.material_name_list]
+        case _:
+            assert False, f'Invalid material order mode: {options.material_order_mode}'
+
+    for material in materials:
         psk_material = Psk.Material()
         psk_material.name = convert_string_to_cp1252_bytes(material.name)
         psk_material.texture_index = len(psk.materials)
@@ -243,9 +186,11 @@ def build_psk(context, input_objects: PskInputObjects, options: PskBuildOptions)
         psk_material.name = convert_string_to_cp1252_bytes('None')
         psk.materials.append(psk_material)
 
-    context.window_manager.progress_begin(0, len(input_objects.mesh_objects))
+    context.window_manager.progress_begin(0, len(input_objects.mesh_dfs_objects))
 
+    coordinate_system_matrix = get_coordinate_system_transform(options.forward_axis, options.up_axis)
     mesh_export_space_matrix = _get_mesh_export_space_matrix(armature_objects, options.export_space)
+    scale_matrix = Matrix.Scale(options.scale, 4)
     vertex_transform_matrix = scale_matrix @ coordinate_system_matrix @ mesh_export_space_matrix
 
     original_armature_object_pose_positions = {armature_object: armature_object.data.pose_position for armature_object in armature_objects}
@@ -255,9 +200,9 @@ def build_psk(context, input_objects: PskInputObjects, options: PskBuildOptions)
     for armature_object in armature_objects:
         armature_object.data.pose_position = 'REST'
 
-    material_names = [m.name for m in options.materials]
+    material_names = [m.name for m in materials]
 
-    for object_index, input_mesh_object in enumerate(input_objects.mesh_objects):
+    for object_index, input_mesh_object in enumerate(input_objects.mesh_dfs_objects):
         obj, instance_objects, matrix_world = input_mesh_object.obj, input_mesh_object.instance_objects, input_mesh_object.matrix_world
 
         armature_object = get_armature_for_mesh_object(obj)
@@ -384,11 +329,11 @@ def build_psk(context, input_objects: PskInputObjects, options: PskBuildOptions)
         # Weights
         if armature_object is not None:
             armature_data = typing.cast(Armature, armature_object.data)
-            bone_index_offset = armature_object_root_bone_indices[armature_object]
+            bone_index_offset = psx_bone_create_result.armature_object_root_bone_indices[armature_object]
             # Because the vertex groups may contain entries for which there is no matching bone in the armature,
             # we must filter them out and not export any weights for these vertex groups.
 
-            bone_names = armature_object_bone_names[armature_object]
+            bone_names = psx_bone_create_result.armature_object_bone_names[armature_object]
             vertex_group_names = [x.name for x in mesh_object.vertex_groups]
             vertex_group_bone_indices: Dict[int, int] = dict()
             for vertex_group_index, vertex_group_name in enumerate(vertex_group_names):
@@ -433,7 +378,7 @@ def build_psk(context, input_objects: PskInputObjects, options: PskBuildOptions)
                     vertices_assigned_weights[vertex_index] = True
 
             # Assign vertices that have not been assigned weights to the root bone of the armature.
-            fallback_weight_bone_index = armature_object_root_bone_indices[armature_object]
+            fallback_weight_bone_index = psx_bone_create_result.armature_object_root_bone_indices[armature_object]
             for vertex_index, assigned in enumerate(vertices_assigned_weights):
                 if not assigned:
                     w = Psk.Weight()
diff --git a/io_scene_psk_psa/psk/data.py b/io_scene_psk_psa/psk/data.py
index a060229..16e991c 100644
--- a/io_scene_psk_psa/psk/data.py
+++ b/io_scene_psk_psa/psk/data.py
@@ -1,6 +1,7 @@
+from ctypes import Structure, c_uint32, c_float, c_int32, c_uint8, c_int8, c_int16, c_char, c_uint16
 from typing import List
 
-from ..shared.data import *
+from ..shared.data import Vector3, Quaternion, Color, Vector2, PsxBone
 
 
 class Psk(object):
@@ -118,7 +119,7 @@ class Psk(object):
         self.faces: List[Psk.Face] = []
         self.materials: List[Psk.Material] = []
         self.weights: List[Psk.Weight] = []
-        self.bones: List[Psk.Bone] = []
+        self.bones: List[PsxBone] = []
         self.extra_uvs: List[Vector2] = []
         self.vertex_colors: List[Color] = []
         self.vertex_normals: List[Vector3] = []
diff --git a/io_scene_psk_psa/psk/export/operators.py b/io_scene_psk_psa/psk/export/operators.py
index 0725f37..f737c2d 100644
--- a/io_scene_psk_psa/psk/export/operators.py
+++ b/io_scene_psk_psa/psk/export/operators.py
@@ -2,7 +2,7 @@ from pathlib import Path
 from typing import List, Optional, cast, Iterable
 
 import bpy
-from bpy.props import StringProperty
+from bpy.props import StringProperty, BoolProperty
 from bpy.types import Operator, Context, Object, Collection, SpaceProperties, Depsgraph, Material
 from bpy_extras.io_utils import ExportHelper
 
@@ -27,8 +27,14 @@ def get_materials_for_mesh_objects(depsgraph: Depsgraph, mesh_objects: Iterable[
                 yield material
 
 
-def populate_material_name_list(depsgraph: Depsgraph, mesh_objects, material_list):
-    materials = get_materials_for_mesh_objects(depsgraph, mesh_objects)
+def populate_material_name_list(depsgraph: Depsgraph, mesh_objects: Iterable[Object], material_list):
+    materials = list(get_materials_for_mesh_objects(depsgraph, mesh_objects))
+
+    # Order the mesh object materials by the order any existing entries in the material list.
+    # This way, if the user has already set up the material list, we don't change the order.
+    material_names = [x.material_name for x in material_list]
+    materials = get_sorted_materials_by_names(materials, material_names)
+
     material_list.clear()
     for index, material in enumerate(materials):
         m = material_list.add()
@@ -60,8 +66,8 @@ def get_collection_export_operator_from_context(context: Context) -> Optional[ob
     return exporter.export_properties
 
 
-class PSK_OT_populate_bone_collection_list(Operator):
-    bl_idname = 'psk.export_populate_bone_collection_list'
+class PSK_OT_bone_collection_list_populate(Operator):
+    bl_idname = 'psk.bone_collection_list_populate'
     bl_label = 'Populate Bone Collection List'
     bl_description = 'Populate the bone collection list from the armature that will be used in this collection export'
     bl_options = {'INTERNAL'}
@@ -83,6 +89,24 @@ class PSK_OT_populate_bone_collection_list(Operator):
         return {'FINISHED'}
 
 
+class PSK_OT_bone_collection_list_select_all(Operator):
+    bl_idname = 'psk.bone_collection_list_select_all'
+    bl_label = 'Select All'
+    bl_description = 'Select all bone collections'
+    bl_options = {'INTERNAL'}
+
+    is_selected: BoolProperty(default=True)
+
+    def execute(self, context):
+        export_operator = get_collection_export_operator_from_context(context)
+        if export_operator is None:
+            self.report({'ERROR_INVALID_CONTEXT'}, 'No valid export operator found in context')
+            return {'CANCELLED'}
+        for item in export_operator.bone_collection_list:
+            item.is_selected = self.is_selected
+        return {'FINISHED'}
+
+
 class PSK_OT_populate_material_name_list(Operator):
     bl_idname = 'psk.export_populate_material_name_list'
     bl_label = 'Populate Material Name List'
@@ -97,7 +121,7 @@ class PSK_OT_populate_material_name_list(Operator):
         depsgraph = context.evaluated_depsgraph_get()
         input_objects = get_psk_input_objects_for_collection(context.collection)
         try:
-            populate_material_name_list(depsgraph, [x.obj for x in input_objects.mesh_objects], export_operator.material_name_list)
+            populate_material_name_list(depsgraph, [x.obj for x in input_objects.mesh_dfs_objects], export_operator.material_name_list)
         except RuntimeError as e:
             self.report({'ERROR_INVALID_CONTEXT'}, str(e))
             return {'CANCELLED'}
@@ -116,7 +140,7 @@ class PSK_OT_material_list_name_add(Operator):
     bl_description = 'Add a material to the material name list (useful if you want to add a material slot that is not actually used in the mesh)'
     bl_options = {'INTERNAL'}
 
-    name: StringProperty(search=material_list_names_search_cb)
+    name: StringProperty(search=material_list_names_search_cb, name='Material Name', default='None')
 
     def invoke(self, context, event):
         return context.window_manager.invoke_props_dialog(self)
@@ -232,7 +256,7 @@ def get_sorted_materials_by_names(materials: Iterable[Material], material_names:
     return materials_in_collection + materials_not_in_collection
 
 
-def get_psk_build_options_from_property_group(pg: 'PSK_PG_export') -> PskBuildOptions:
+def get_psk_build_options_from_property_group(pg: PskExportMixin) -> PskBuildOptions:
     options = PskBuildOptions()
     options.object_eval_state = pg.object_eval_state
     options.export_space = pg.export_space
@@ -242,15 +266,8 @@ def get_psk_build_options_from_property_group(pg: 'PSK_PG_export') -> PskBuildOp
     options.forward_axis = pg.forward_axis
     options.up_axis = pg.up_axis
     options.root_bone_name = pg.root_bone_name
-
-    # TODO: perhaps move this into the build function and replace the materials list with a material names list.
-    # materials = get_materials_for_mesh_objects(depsgraph, mesh_objects)
-
-    # The material name list may contain materials that are not on the mesh objects.
-    # Therefore, we can perhaps take the material_name_list as gospel and simply use it as a lookup table.
-    # If a look-up fails, replace it with an empty material.
-    options.materials = [bpy.data.materials.get(x.material_name, None) for x in pg.material_name_list]
-
+    options.material_order_mode = pg.material_order_mode
+    options.material_name_list = pg.material_name_list
     return options
 
 
@@ -319,9 +336,16 @@ class PSK_OT_export_collection(Operator, ExportHelper, PskExportMixin):
             draw_bone_filter_mode(bones_panel, self, True)
 
             if self.bone_filter_mode == 'BONE_COLLECTIONS':
-                bones_panel.operator(PSK_OT_populate_bone_collection_list.bl_idname, icon='FILE_REFRESH')
+                row = bones_panel.row()
                 rows = max(3, min(len(self.bone_collection_list), 10))
-                bones_panel.template_list('PSX_UL_bone_collection_list', '', self, 'bone_collection_list', self, 'bone_collection_list_index', rows=rows)
+                row.template_list('PSX_UL_bone_collection_list', '', self, 'bone_collection_list', self, 'bone_collection_list_index', rows=rows)
+                col = row.column(align=True)
+                col.operator(PSK_OT_bone_collection_list_populate.bl_idname, text='', icon='FILE_REFRESH')
+                col.separator()
+                op = col.operator(PSK_OT_bone_collection_list_select_all.bl_idname, text='', icon='CHECKBOX_HLT')
+                op.is_selected = True
+                op = col.operator(PSK_OT_bone_collection_list_select_all.bl_idname, text='', icon='CHECKBOX_DEHLT')
+                op.is_selected = False
 
             advanced_bones_header, advanced_bones_panel = bones_panel.panel('Advanced', default_closed=True)
             advanced_bones_header.label(text='Advanced')
@@ -336,15 +360,22 @@ class PSK_OT_export_collection(Operator, ExportHelper, PskExportMixin):
         materials_header.label(text='Materials', icon='MATERIAL')
 
         if materials_panel:
-            materials_panel.operator(PSK_OT_populate_material_name_list.bl_idname, icon='FILE_REFRESH')
-            rows = max(3, min(len(self.material_name_list), 10))
-            row = materials_panel.row()
-            row.template_list('PSK_UL_material_names', '', self, 'material_name_list', self, 'material_name_list_index', rows=rows)
-            col = row.column(align=True)
-            col.operator(PSK_OT_material_list_name_move_up.bl_idname, text='', icon='TRIA_UP')
-            col.operator(PSK_OT_material_list_name_move_down.bl_idname, text='', icon='TRIA_DOWN')
-            col.separator()
-            col.operator(PSK_OT_material_list_name_add.bl_idname, text='', icon='ADD')
+            flow = materials_panel.grid_flow(row_major=True)
+            flow.use_property_split = True
+            flow.use_property_decorate = False
+            flow.prop(self, 'material_order_mode', text='Material Order')
+
+            if self.material_order_mode == 'MANUAL':
+                rows = max(3, min(len(self.material_name_list), 10))
+                row = materials_panel.row()
+                row.template_list('PSK_UL_material_names', '', self, 'material_name_list', self, 'material_name_list_index', rows=rows)
+                col = row.column(align=True)
+                col.operator(PSK_OT_populate_material_name_list.bl_idname, text='', icon='FILE_REFRESH')
+                col.separator()
+                col.operator(PSK_OT_material_list_name_move_up.bl_idname, text='', icon='TRIA_UP')
+                col.operator(PSK_OT_material_list_name_move_down.bl_idname, text='', icon='TRIA_DOWN')
+                col.separator()
+                col.operator(PSK_OT_material_list_name_add.bl_idname, text='', icon='ADD')
 
         # Transform
         transform_header, transform_panel = layout.panel('Transform', default_closed=False)
@@ -364,7 +395,7 @@ class PSK_OT_export(Operator, ExportHelper):
     bl_idname = 'psk.export'
     bl_label = 'Export'
     bl_options = {'INTERNAL', 'UNDO'}
-    bl_description = 'Export mesh and armature to PSK'
+    bl_description = 'Export selected meshes to PSK'
     filename_ext = '.psk'
     filter_glob: StringProperty(default='*.psk', options={'HIDDEN'})
     filepath: StringProperty(
@@ -387,7 +418,7 @@ class PSK_OT_export(Operator, ExportHelper):
         depsgraph = context.evaluated_depsgraph_get()
 
         try:
-            populate_material_name_list(depsgraph, [x.obj for x in input_objects.mesh_objects], pg.material_name_list)
+            populate_material_name_list(depsgraph, [x.obj for x in input_objects.mesh_dfs_objects], pg.material_name_list)
         except RuntimeError as e:
             self.report({'ERROR_INVALID_CONTEXT'}, str(e))
             return {'CANCELLED'}
@@ -419,17 +450,30 @@ class PSK_OT_export(Operator, ExportHelper):
                 row = bones_panel.row()
                 rows = max(3, min(len(pg.bone_collection_list), 10))
                 row.template_list('PSX_UL_bone_collection_list', '', pg, 'bone_collection_list', pg, 'bone_collection_list_index', rows=rows)
+            bones_advanced_header, bones_advanced_panel = bones_panel.panel('Advanced', default_closed=True)
+            bones_advanced_header.label(text='Advanced')
+            if bones_advanced_panel:
+                flow = bones_advanced_panel.grid_flow(row_major=True)
+                flow.use_property_split = True
+                flow.use_property_decorate = False
+                flow.prop(pg, 'root_bone_name')
 
         # Materials
         materials_header, materials_panel = layout.panel('Materials', default_closed=False)
         materials_header.label(text='Materials', icon='MATERIAL')
         if materials_panel:
-            row = materials_panel.row()
-            rows = max(3, min(len(pg.bone_collection_list), 10))
-            row.template_list('PSK_UL_material_names', '', pg, 'material_name_list', pg, 'material_name_list_index', rows=rows)
-            col = row.column(align=True)
-            col.operator(PSK_OT_material_list_move_up.bl_idname, text='', icon='TRIA_UP')
-            col.operator(PSK_OT_material_list_move_down.bl_idname, text='', icon='TRIA_DOWN')
+            flow = materials_panel.grid_flow(row_major=True)
+            flow.use_property_split = True
+            flow.use_property_decorate = False
+            flow.prop(pg, 'material_order_mode', text='Material Order')
+
+            if pg.material_order_mode == 'MANUAL':
+                row = materials_panel.row()
+                rows = max(3, min(len(pg.bone_collection_list), 10))
+                row.template_list('PSK_UL_material_names', '', pg, 'material_name_list', pg, 'material_name_list_index', rows=rows)
+                col = row.column(align=True)
+                col.operator(PSK_OT_material_list_move_up.bl_idname, text='', icon='TRIA_UP')
+                col.operator(PSK_OT_material_list_move_down.bl_idname, text='', icon='TRIA_DOWN')
 
         # Transform
         transform_header, transform_panel = layout.panel('Transform', default_closed=False)
@@ -470,7 +514,8 @@ classes = (
     PSK_OT_material_list_move_down,
     PSK_OT_export,
     PSK_OT_export_collection,
-    PSK_OT_populate_bone_collection_list,
+    PSK_OT_bone_collection_list_populate,
+    PSK_OT_bone_collection_list_select_all,
     PSK_OT_populate_material_name_list,
     PSK_OT_material_list_name_move_up,
     PSK_OT_material_list_name_move_down,
diff --git a/io_scene_psk_psa/psk/export/properties.py b/io_scene_psk_psa/psk/export/properties.py
index 1ea55fe..588253d 100644
--- a/io_scene_psk_psa/psk/export/properties.py
+++ b/io_scene_psk_psa/psk/export/properties.py
@@ -12,6 +12,11 @@ object_eval_state_items = (
     ('ORIGINAL', 'Original', 'Use data from original object with no modifiers applied'),
 )
 
+material_order_mode_items = (
+    ('AUTOMATIC', 'Automatic', 'Automatically order the materials'),
+    ('MANUAL', 'Manual', 'Manually arrange the materials'),
+)
+
 class PSK_PG_material_list_item(PropertyGroup):
     material: PointerProperty(type=Material)
     index: IntProperty()
@@ -47,6 +52,12 @@ class PskExportMixin(ExportSpaceMixin, ForwardUpAxisMixin):
     )
     bone_collection_list: CollectionProperty(type=PSX_PG_bone_collection_list_item)
     bone_collection_list_index: IntProperty(default=0)
+    material_order_mode: EnumProperty(
+        name='Material Order',
+        description='The order in which to export the materials',
+        items=material_order_mode_items,
+        default='AUTOMATIC'
+    )
     material_name_list: CollectionProperty(type=PSK_PG_material_name_list_item)
     material_name_list_index: IntProperty(default=0)
     root_bone_name: StringProperty(
diff --git a/io_scene_psk_psa/psk/export/ui.py b/io_scene_psk_psa/psk/export/ui.py
index 2412d19..37645ad 100644
--- a/io_scene_psk_psa/psk/export/ui.py
+++ b/io_scene_psk_psa/psk/export/ui.py
@@ -6,7 +6,8 @@ class PSK_UL_material_names(UIList):
     def draw_item(self, context, layout, data, item, icon, active_data, active_propname, index):
         row = layout.row()
         material = bpy.data.materials.get(item.material_name, None)
-        row.prop(item, 'material_name', text='', emboss=False, icon_value=layout.icon(material) if material else 0)
+        icon_value = layout.icon(material) if material else 0
+        row.prop(item, 'material_name', text='', emboss=False, icon_value=icon_value, icon='BLANK1' if icon_value == 0 else 'NONE')
 
 
 classes = (
diff --git a/io_scene_psk_psa/psk/importer.py b/io_scene_psk_psa/psk/importer.py
index 8b9bdbf..753d930 100644
--- a/io_scene_psk_psa/psk/importer.py
+++ b/io_scene_psk_psa/psk/importer.py
@@ -8,6 +8,7 @@ from mathutils import Quaternion, Vector, Matrix
 
 from .data import Psk
 from .properties import poly_flags_to_triangle_type_and_bit_flags
+from ..shared.data import PsxBone
 from ..shared.helpers import rgb_to_srgb, is_bdk_addon_loaded
 
 
@@ -31,9 +32,9 @@ class ImportBone:
     '''
     Intermediate bone type for the purpose of construction.
     '''
-    def __init__(self, index: int, psk_bone: Psk.Bone):
+    def __init__(self, index: int, psk_bone: PsxBone):
         self.index: int = index
-        self.psk_bone: Psk.Bone = psk_bone
+        self.psk_bone: PsxBone = psk_bone
         self.parent: Optional[ImportBone] = None
         self.local_rotation: Quaternion = Quaternion()
         self.local_translation: Vector = Vector()
diff --git a/io_scene_psk_psa/psk/reader.py b/io_scene_psk_psa/psk/reader.py
index 49864a6..7feb8fc 100644
--- a/io_scene_psk_psa/psk/reader.py
+++ b/io_scene_psk_psa/psk/reader.py
@@ -53,7 +53,7 @@ def read_psk(path: str) -> Psk:
                 case b'MATT0000':
                     _read_types(fp, Psk.Material, section, psk.materials)
                 case b'REFSKELT':
-                    _read_types(fp, Psk.Bone, section, psk.bones)
+                    _read_types(fp, PsxBone, section, psk.bones)
                 case b'RAWWEIGHTS':
                     _read_types(fp, Psk.Weight, section, psk.weights)
                 case b'FACE3200':
diff --git a/io_scene_psk_psa/psk/writer.py b/io_scene_psk_psa/psk/writer.py
index 8bf7708..c49011e 100644
--- a/io_scene_psk_psa/psk/writer.py
+++ b/io_scene_psk_psa/psk/writer.py
@@ -3,7 +3,7 @@ from ctypes import Structure, sizeof
 from typing import Type
 
 from .data import Psk
-from ..shared.data import Section, Vector3
+from ..shared.data import Section, Vector3, PsxBone
 
 MAX_WEDGE_COUNT = 65536
 MAX_POINT_COUNT = 4294967296
@@ -55,7 +55,7 @@ def write_psk(psk: Psk, path: str):
             _write_section(fp, b'VTXW0000', Psk.Wedge16, wedges)
             _write_section(fp, b'FACE0000', Psk.Face, psk.faces)
             _write_section(fp, b'MATT0000', Psk.Material, psk.materials)
-            _write_section(fp, b'REFSKELT', Psk.Bone, psk.bones)
+            _write_section(fp, b'REFSKELT', PsxBone, psk.bones)
             _write_section(fp, b'RAWWEIGHTS', Psk.Weight, psk.weights)
     except PermissionError as e:
         raise RuntimeError(f'The current user "{os.getlogin()}" does not have permission to write to "{path}"') from e
diff --git a/io_scene_psk_psa/shared/data.py b/io_scene_psk_psa/shared/data.py
index 7ec8d39..eabbae3 100644
--- a/io_scene_psk_psa/shared/data.py
+++ b/io_scene_psk_psa/shared/data.py
@@ -2,7 +2,7 @@ from ctypes import *
 from typing import Tuple
 
 from bpy.props import EnumProperty
-from mathutils import Vector, Matrix, Quaternion as BpyQuaternion
+from mathutils import Quaternion as BpyQuaternion
 
 
 class Color(Structure):
@@ -94,6 +94,19 @@ class Quaternion(Structure):
         return quaternion
 
 
+class PsxBone(Structure):
+    _fields_ = [
+        ('name', c_char * 64),
+        ('flags', c_int32),
+        ('children_count', c_int32),
+        ('parent_index', c_int32),
+        ('rotation', Quaternion),
+        ('location', Vector3),
+        ('length', c_float),
+        ('size', Vector3)
+    ]
+
+
 class Section(Structure):
     _fields_ = [
         ('name', c_char * 20),
@@ -171,30 +184,3 @@ class ExportSpaceMixin:
         items=export_space_items,
         default='WORLD'
     )
-
-def get_vector_from_axis_identifier(axis_identifier: str) -> Vector:
-    match axis_identifier:
-        case 'X':
-            return Vector((1.0, 0.0, 0.0))
-        case 'Y':
-            return Vector((0.0, 1.0, 0.0))
-        case 'Z':
-            return Vector((0.0, 0.0, 1.0))
-        case '-X':
-            return Vector((-1.0, 0.0, 0.0))
-        case '-Y':
-            return Vector((0.0, -1.0, 0.0))
-        case '-Z':
-            return Vector((0.0, 0.0, -1.0))
-
-
-def get_coordinate_system_transform(forward_axis: str = 'X', up_axis: str = 'Z') -> Matrix:
-    forward = get_vector_from_axis_identifier(forward_axis)
-    up = get_vector_from_axis_identifier(up_axis)
-    left = up.cross(forward)
-    return Matrix((
-        (forward.x, forward.y, forward.z, 0.0),
-        (left.x, left.y, left.z, 0.0),
-        (up.x, up.y, up.z, 0.0),
-        (0.0, 0.0, 0.0, 1.0)
-    ))
diff --git a/io_scene_psk_psa/shared/helpers.py b/io_scene_psk_psa/shared/helpers.py
index 2ba74bc..f6bd219 100644
--- a/io_scene_psk_psa/shared/helpers.py
+++ b/io_scene_psk_psa/shared/helpers.py
@@ -1,12 +1,14 @@
-from typing import List, Iterable, cast, Optional
+from collections import Counter
+from typing import List, Iterable, cast, Optional, Dict, Tuple
 
 import bpy
 from bpy.props import CollectionProperty
 from bpy.types import AnimData, Object
 from bpy.types import Armature
-from mathutils import Matrix
+from mathutils import Matrix, Vector
 
-from .data import get_coordinate_system_transform
+from .data import Vector3, Quaternion
+from ..shared.data import PsxBone
 
 
 def rgb_to_srgb(c: float):
@@ -171,16 +173,15 @@ def convert_string_to_cp1252_bytes(string: str) -> bytes:
 
 
 # TODO: Perhaps export space should just be a transform matrix, since the below is not actually used unless we're using WORLD space.
-def convert_blender_bones_to_psx_bones(
-        bones: Iterable[bpy.types.Bone],
-        bone_class: type,
+def create_psx_bones_from_blender_bones(
+        bones: List[bpy.types.Bone],
         export_space: str = 'WORLD',
         armature_object_matrix_world: Matrix = Matrix.Identity(4),
         scale = 1.0,
         forward_axis: str = 'X',
         up_axis: str = 'Z',
         root_bone: Optional = None,
-) -> Iterable:
+) -> List[PsxBone]:
 
     scale_matrix = Matrix.Scale(scale, 4)
 
@@ -189,7 +190,7 @@ def convert_blender_bones_to_psx_bones(
 
     psx_bones = []
     for bone in bones:
-        psx_bone = bone_class()
+        psx_bone = PsxBone()
         psx_bone.name = convert_string_to_cp1252_bytes(bone.name)
 
         try:
@@ -282,3 +283,148 @@ def get_export_space_matrix(export_space: str, armature_object: Optional[Object]
             pass
         case _:
             assert False, f'Invalid export space: {export_space}'
+
+
+class PsxBoneCreateResult:
+    def __init__(self,
+                 bones: List[Tuple[PsxBone, Optional[Object]]],  # List of tuples of (psx_bone, armature_object)
+                 armature_object_root_bone_indices: Dict[Object, int],
+                 armature_object_bone_names: Dict[Object, List[str]],
+                 ):
+        self.bones = bones
+        self.armature_object_root_bone_indices = armature_object_root_bone_indices
+        self.armature_object_bone_names = armature_object_bone_names
+
+
+def create_psx_bones(
+        armature_objects: List[Object],
+        export_space: str = 'WORLD',
+        root_bone_name: str = 'ROOT',
+        forward_axis: str = 'X',
+        up_axis: str = 'Z',
+        scale: float = 1.0,
+        bone_filter_mode: str = 'ALL',
+        bone_collection_indices: Optional[List[Tuple[str, int]]] = None,
+) -> PsxBoneCreateResult:
+    '''
+    Creates a list of PSX bones from the given armature objects and options.
+    This function will throw a RuntimeError if multiple armature objects are passed in and the export space is not WORLD.
+    It will also throw a RuntimeError if the bone names are not unique when compared case-insensitively.
+    '''
+    if bone_collection_indices is None:
+        bone_collection_indices = []
+
+    bones: List[Tuple[PsxBone, Optional[Object]]] = []
+
+    if export_space != 'WORLD' and len(armature_objects) > 1:
+        raise RuntimeError('When exporting multiple armatures, the Export Space must be World')
+
+    coordinate_system_matrix = get_coordinate_system_transform(forward_axis, up_axis)
+    coordinate_system_default_rotation = coordinate_system_matrix.to_quaternion()
+
+    total_bone_count = sum(len(armature_object.data.bones) for armature_object in armature_objects)
+
+    # Store the index of the root bone for each armature object.
+    # We will need this later to correctly assign vertex weights.
+    armature_object_root_bone_indices = dict()
+
+    # Store the bone names to be exported for each armature object.
+    armature_object_bone_names: Dict[Object, List[str]] = dict()
+    for armature_object in  armature_objects:
+        armature_bone_collection_indices = [x[1] for x in bone_collection_indices if x[0] == armature_object.name]
+        bone_names = get_export_bone_names(armature_object, bone_filter_mode, armature_bone_collection_indices)
+        armature_object_bone_names[armature_object] = bone_names
+
+    if len(armature_objects) == 0 or total_bone_count == 0:
+        # If the mesh has no armature object or no bones, simply assign it a dummy bone at the root to satisfy the
+        # requirement that a PSK file must have at least one bone.
+        psx_bone = PsxBone()
+        psx_bone.name = convert_string_to_cp1252_bytes(root_bone_name)
+        psx_bone.flags = 0
+        psx_bone.children_count = 0
+        psx_bone.parent_index = 0
+        psx_bone.location = Vector3.zero()
+        psx_bone.rotation = Quaternion.from_bpy_quaternion(coordinate_system_default_rotation)
+        bones.append((psx_bone, None))
+
+        armature_object_root_bone_indices[None] = 0
+    else:
+        # If we have multiple armature objects, create a root bone at the world origin.
+        if len(armature_objects) > 1:
+            psx_bone = PsxBone()
+            psx_bone.name = convert_string_to_cp1252_bytes(root_bone_name)
+            psx_bone.flags = 0
+            psx_bone.children_count = total_bone_count
+            psx_bone.parent_index = 0
+            psx_bone.location = Vector3.zero()
+            psx_bone.rotation = Quaternion.from_bpy_quaternion(coordinate_system_default_rotation)
+            bones.append((psx_bone, None))
+
+            armature_object_root_bone_indices[None] = 0
+
+        root_bone = bones[0][0] if len(bones) > 0 else None
+
+        for armature_object in armature_objects:
+            bone_names = armature_object_bone_names[armature_object]
+            armature_data = cast(Armature, armature_object.data)
+            armature_bones = [armature_data.bones[bone_name] for bone_name in bone_names]
+
+            armature_psx_bones = create_psx_bones_from_blender_bones(
+                bones=armature_bones,
+                export_space=export_space,
+                armature_object_matrix_world=armature_object.matrix_world,
+                scale=scale,
+                forward_axis=forward_axis,
+                up_axis=up_axis,
+                root_bone=root_bone,
+            )
+
+            # If we are appending these bones to an existing list of bones, we need to adjust the parent indices.
+            if len(bones) > 0:
+                parent_index_offset = len(bones)
+                for bone in armature_psx_bones[1:]:
+                    bone.parent_index += parent_index_offset
+
+            armature_object_root_bone_indices[armature_object] = len(bones)
+
+            bones.extend((psx_bone, armature_object) for psx_bone in armature_psx_bones)
+
+    # Check if there are bone name conflicts between armatures.
+    bone_name_counts = Counter(bone[0].name.decode('windows-1252').upper() for bone in bones)
+    for bone_name, count in bone_name_counts.items():
+        if count > 1:
+            raise RuntimeError(f'Found {count} bones with the name "{bone_name}". Bone names must be unique when compared case-insensitively.')
+
+    return PsxBoneCreateResult(
+        bones=bones,
+        armature_object_root_bone_indices=armature_object_root_bone_indices,
+        armature_object_bone_names=armature_object_bone_names,
+    )
+
+
+def get_vector_from_axis_identifier(axis_identifier: str) -> Vector:
+    match axis_identifier:
+        case 'X':
+            return Vector((1.0, 0.0, 0.0))
+        case 'Y':
+            return Vector((0.0, 1.0, 0.0))
+        case 'Z':
+            return Vector((0.0, 0.0, 1.0))
+        case '-X':
+            return Vector((-1.0, 0.0, 0.0))
+        case '-Y':
+            return Vector((0.0, -1.0, 0.0))
+        case '-Z':
+            return Vector((0.0, 0.0, -1.0))
+
+
+def get_coordinate_system_transform(forward_axis: str = 'X', up_axis: str = 'Z') -> Matrix:
+    forward = get_vector_from_axis_identifier(forward_axis)
+    up = get_vector_from_axis_identifier(up_axis)
+    left = up.cross(forward)
+    return Matrix((
+        (forward.x, forward.y, forward.z, 0.0),
+        (left.x, left.y, left.z, 0.0),
+        (up.x, up.y, up.z, 0.0),
+        (0.0, 0.0, 0.0, 1.0)
+    ))