diff --git a/io_scene_a3d/A3D.py b/io_scene_a3d/A3D.py
index 97b685b..8725ec6 100644
--- a/io_scene_a3d/A3D.py
+++ b/io_scene_a3d/A3D.py
@@ -139,7 +139,19 @@ class A3D:
         stream.read(padding)
 
     def writeRootBlock3(self, stream):
-        raise RuntimeError("Version 3 files are not supported yet")
+        buffer = BytesIO()
+
+        # Write data to the buffer
+        print("Writing root block")
+        self.writeMaterialBlock3(buffer)
+        self.writeMeshBlock3(buffer)
+        self.writeTransformBlock3(buffer)
+        self.writeObjectBlock3(buffer)
+
+        # Write buffer to stream
+        packStream("<2I", stream, A3D_ROOTBLOCK_SIGNATURE, buffer.tell())
+        buffer.seek(0, 0)
+        stream.write(buffer.read())
 
     '''
     Material data blocks
@@ -188,6 +200,24 @@ class A3D:
         padding = calculatePadding(length)
         stream.read(padding)
 
+    def writeMaterialBlock3(self, stream):
+        buffer = BytesIO()
+
+        # Write data to the buffer
+        print("Writing material block")
+        packStream("<I", buffer, len(self.materials))
+        for material in self.materials:
+            material.write3(buffer)
+
+        # Write buffer to stream
+        packStream("<2I", stream, A3D_MATERIALBLOCK_SIGNATURE, buffer.tell())
+        buffer.seek(0, 0)
+        stream.write(buffer.read())
+
+        # Padding
+        paddingSize = calculatePadding(buffer.tell())
+        stream.write(b"\x00" * paddingSize)
+
     '''
     Mesh data blocks
     '''
@@ -235,6 +265,24 @@ class A3D:
         padding = calculatePadding(length)
         stream.read(padding)
 
+    def writeMeshBlock3(self, stream):
+        buffer = BytesIO()
+
+        # Write data to the buffer
+        print("Writing mesh block")
+        packStream("<I", buffer, len(self.meshes))
+        for mesh in self.meshes:
+            mesh.write3(buffer)
+
+        # Write buffer to stream
+        packStream("<2I", stream, A3D_MESHBLOCK_SIGNATURE, buffer.tell())
+        buffer.seek(0, 0)
+        stream.write(buffer.read())
+
+        # Padding
+        paddingSize = calculatePadding(buffer.tell())
+        stream.write(b"\x00" * paddingSize)
+
     '''
     Transform data blocks
     '''
@@ -279,7 +327,6 @@ class A3D:
 
         # Read data
         print(f"Reading transform block with {transformCount} transforms and length {length}")
-        transforms = []
         for _ in range(transformCount):
             transform = A3DObjects.A3DTransform()
             transform.read3(stream)
@@ -293,6 +340,26 @@ class A3D:
         padding = calculatePadding(length)
         stream.read(padding)
 
+    def writeTransformBlock3(self, stream):
+        buffer = BytesIO()
+
+        # Write data to the buffer
+        print("Writing transform block")
+        packStream("<I", buffer, len(self.transforms))
+        for transform in self.transforms:
+            transform.write3(buffer)
+        for parentID in self.transformParentIDs:
+            packStream("<i", buffer, parentID)
+
+        # Write buffer to stream
+        packStream("<2I", stream, A3D_TRANSFORMBLOCK_SIGNATURE, buffer.tell())
+        buffer.seek(0, 0)
+        stream.write(buffer.read())
+
+        # Padding
+        paddingSize = calculatePadding(buffer.tell())
+        stream.write(b"\x00" * paddingSize)
+
     '''
     Object data blocks
     '''
@@ -338,4 +405,22 @@ class A3D:
 
         # Padding
         padding = calculatePadding(length)
-        stream.read(padding)
\ No newline at end of file
+        stream.read(padding)
+
+    def writeObjectBlock3(self, stream):
+        buffer = BytesIO()
+
+        # Write data to the buffer
+        print("Writing object block")
+        packStream("<I", buffer, len(self.objects))
+        for objec in self.objects:
+            objec.write3(buffer)
+
+        # Write buffer to stream
+        packStream("<2I", stream, A3D_OBJECTBLOCK_SIGNATURE, buffer.tell())
+        buffer.seek(0, 0)
+        stream.write(buffer.read())
+
+        # Padding
+        paddingSize = calculatePadding(buffer.tell())
+        stream.write(b"\x00" * paddingSize)
diff --git a/io_scene_a3d/A3DBlenderExporter.py b/io_scene_a3d/A3DBlenderExporter.py
index 927617e..2dae96c 100644
--- a/io_scene_a3d/A3DBlenderExporter.py
+++ b/io_scene_a3d/A3DBlenderExporter.py
@@ -31,9 +31,10 @@ from .A3DObjects import (
 )
 
 class A3DBlenderExporter:
-    def __init__(self, modelData, objects):
+    def __init__(self, modelData, objects, version=2):
         self.modelData = modelData
         self.objects = objects
+        self.version = version
 
     def exportData(self):
         print("Exporting blender data to A3D")
@@ -60,7 +61,7 @@ class A3DBlenderExporter:
 
                 materials[ma.name] = materialData
             # Create mesh
-            mesh = self.buildA3DMesh(me)
+            mesh = self.buildA3DMesh(me, ob)
             meshes.append(mesh)
             # Create transform
             transform = A3DObjects.A3DTransform()
@@ -68,22 +69,34 @@ class A3DBlenderExporter:
             rotationW, rotationX, rotationY, rotationZ = ob.rotation_quaternion
             transform.rotation = (rotationX, rotationY, rotationZ, rotationW)
             transform.scale = ob.scale
+            transform.name = ob.name
             transforms[ob.name] = transform
             # Create object
             objec = A3DObjects.A3DObject()
             objec.name = ob.name
             objec.meshID = len(meshes) - 1
             objec.transformID = len(transforms) - 1
+            materialIDs = []
+            for ma in me.materials:
+                materialID = list(materials.keys()).index(ma.name)
+                materialIDs.append(materialID)
+            objec.materialCount = len(materialIDs)
+            objec.materialIDs = materialIDs
             objects.append(objec)
         # Create parentIDs
         transformParentIDs = []
         for ob in self.objects:
             parentOB = ob.parent
             if (parentOB == None) or (parentOB.name not in transforms):
-                transformParentIDs.append(0) #XXX: this is only for version 2
+                if self.version < 3:
+                    transformParentIDs.append(0)
+                else:
+                    transformParentIDs.append(-1)
             else:
                 parentIndex = list(transforms.keys()).index(parentOB.name)
-                transformParentIDs.append(parentIndex+1)
+                if self.version < 3:
+                    parentIndex += 1 # Version 2 uses 0 to signify empty parent
+                transformParentIDs.append(parentIndex)
 
         self.modelData.materials = materials.values()
         self.modelData.meshes = meshes
@@ -91,7 +104,7 @@ class A3DBlenderExporter:
         self.modelData.transformParentIDs = transformParentIDs
         self.modelData.objects = objects
 
-    def buildA3DMesh(self, me):
+    def buildA3DMesh(self, me, ob):
         mesh = A3DObjects.A3DMesh()
         mesh.vertexCount = len(me.vertices)
 
@@ -137,4 +150,12 @@ class A3DBlenderExporter:
         mesh.submeshCount = len(submeshes)
         mesh.submeshes = submeshes
 
+        # Bound box data
+        bounds = []
+        for bound in ob.bound_box:
+            x, y, z = bound
+            bounds.append((x, y, z))
+        mesh.bboxMax = max(bounds)
+        mesh.bboxMin = min(bounds)
+
         return mesh
diff --git a/io_scene_a3d/A3DObjects.py b/io_scene_a3d/A3DObjects.py
index ba1d7cf..e0298a9 100644
--- a/io_scene_a3d/A3DObjects.py
+++ b/io_scene_a3d/A3DObjects.py
@@ -20,7 +20,7 @@ OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 SOFTWARE.
 '''
 
-from .IOTools import unpackStream, packStream, readNullTerminatedString, writeNullTerminatedString, readLengthPrefixedString, calculatePadding
+from .IOTools import unpackStream, packStream, readNullTerminatedString, writeNullTerminatedString, readLengthPrefixedString, writeLengthPrefixedString, calculatePadding
 
 class A3DMaterial:
     def __init__(self):
@@ -48,6 +48,12 @@ class A3DMaterial:
 
         print(f"[A3DMaterial name: {self.name} color: {self.color} diffuse map: {self.diffuseMap}]")
 
+    def write3(self, stream):
+        writeLengthPrefixedString(stream, self.name)
+        colorR, colorG, colorB = self.color
+        packStream("<3f", stream, colorR, colorG, colorB)
+        writeLengthPrefixedString(stream, self.diffuseMap)
+
 class A3DMesh:
     def __init__(self):
         self.name = ""
@@ -110,6 +116,24 @@ class A3DMesh:
         
         print(f"[A3DMesh name: {self.name} bbox max: {self.bboxMax} bbox min: {self.bboxMin} vertex buffers: {len(self.vertexBuffers)} submeshes: {len(self.submeshes)}]")
 
+    def write3(self, stream):
+        writeLengthPrefixedString(stream, self.name)
+        bboxMaxX, bboxMaxY, bboxMaxZ = self.bboxMax
+        packStream("<3f", stream, bboxMaxX, bboxMaxY, bboxMaxZ)
+        bboxMinX, bboxMinY, bboxMinZ = self.bboxMin
+        packStream("<3f", stream, bboxMinX, bboxMinY, bboxMinZ)
+        packStream("<f", stream, 0.0) # XXX: Unknown float value!
+
+        # Write vertex buffers
+        packStream("<2I", stream, self.vertexCount, self.vertexBufferCount)
+        for vertexBuffer in self.vertexBuffers:
+            vertexBuffer.write2(stream)
+        
+        # Write submeshes
+        packStream("<I", stream, self.submeshCount)
+        for submesh in self.submeshes:
+            submesh.write3(stream)
+
 A3D_VERTEXTYPE_COORDINATE = 1
 A3D_VERTEXTYPE_UV1 = 2
 A3D_VERTEXTYPE_NORMAL1 = 3
@@ -179,11 +203,20 @@ class A3DSubmesh:
         self.indices = list(unpackStream(f"<{self.indexCount}H", stream))
         
         # Padding
-        padding = calculatePadding(self.indexCount*2) # Each index is 2 bytes
-        stream.read(padding)
+        paddingSize = calculatePadding(self.indexCount*2) # Each index is 2 bytes
+        stream.read(paddingSize)
 
         print(f"[A3DSubmesh indices: {len(self.indices)} smoothing groups: {len(self.smoothingGroups)} materialID: {self.materialID}]")
 
+    def write3(self, stream):
+        packStream("<I", stream, self.indexCount)
+        for index in self.indices:
+            packStream("<H", stream, index)
+        
+        # Padding
+        paddingSize = calculatePadding(self.indexCount*2) # Each index is 2 bytes
+        stream.write(b"\x00" * paddingSize)
+
 class A3DTransform:
     def __init__(self):
         self.name = ""
@@ -214,6 +247,15 @@ class A3DTransform:
 
         print(f"[A3DTransform name: {self.name} position: {self.position} rotation: {self.rotation} scale: {self.scale}]")
 
+    def write3(self, stream):
+        writeLengthPrefixedString(stream, self.name)
+        positionX, positionY, positionZ = self.position
+        packStream("<3f", stream, positionX, positionY, positionZ)
+        rotationX, rotationY, rotationZ, rotationW = self.rotation
+        packStream("<4f", stream, rotationX, rotationY, rotationZ, rotationW)
+        scaleX, scaleY, scaleZ = self.scale
+        packStream("<3f", stream, scaleX, scaleY, scaleZ)
+
 class A3DObject:
     def __init__(self):
         self.name = ""
@@ -241,4 +283,9 @@ class A3DObject:
             materialID, = unpackStream("<i", stream)
             self.materialIDs.append(materialID)
 
-        print(f"[A3DObject name: {self.name} meshID: {self.meshID} transformID: {self.transformID} materialIDs: {len(self.materialIDs)}]")
\ No newline at end of file
+        print(f"[A3DObject name: {self.name} meshID: {self.meshID} transformID: {self.transformID} materialIDs: {len(self.materialIDs)}]")
+
+    def write3(self, stream):
+        packStream("<3I", stream, self.meshID, self.transformID, self.materialCount)
+        for materialID in self.materialIDs:
+            packStream("<i", stream, materialID)
diff --git a/io_scene_a3d/IOTools.py b/io_scene_a3d/IOTools.py
index 89971aa..3977210 100644
--- a/io_scene_a3d/IOTools.py
+++ b/io_scene_a3d/IOTools.py
@@ -56,4 +56,13 @@ def readLengthPrefixedString(stream):
     paddingSize = calculatePadding(length)
     stream.read(paddingSize)
 
-    return string.decode("utf8", errors="ignore")
\ No newline at end of file
+    return string.decode("utf8", errors="ignore")
+
+def writeLengthPrefixedString(stream, string):
+    string = string.encode("utf-8")
+
+    packStream("<I", stream, len(string))
+    stream.write(string)
+
+    paddingSize = calculatePadding(len(string))
+    stream.write(b"\x00" * paddingSize)
\ No newline at end of file