I'm trying to manually create a ModelContent instance that includes custom Bone data in a custom ContentProcessor in the XNA Content Pipeline. I can't seem to create or assign manually created bone data due to either private constructors or read-only collections (at every turn). The code I have right now that creates a single triangle ModelContent that I'd like to create a bone for is: MeshContent mc = new MeshContent(); mc.Positions.Add(new Vector3(-10, 0, 0)); mc.Positions.Add(new Vector3(0, 10, 0)); mc.Positions.Add(new Vector3(10, 0, 0)); GeometryContent gc = new GeometryContent(); gc.Indices.AddRange(new int[] { 0, 1, 2 }); gc.Vertices.AddRange(new int[] { 0, 1, 2 }); mc.Geometry.Add(gc); // Create normals MeshHelper.CalculateNormals(mc, true); // finally, convert it to a model ModelContent model = context.Convert<MeshContent, ModelContent>(mc, "ModelProcessor"); The documentation on XNA is amazingly sparse. I've been referencing the class diagrams created by DigitalRune and Sean Hargreaves blog, but I haven't found anything on creating bone content. Once the ModelContent is created, it's not possible to add bones because the Bones collection is read-only. And it seems the only way to create the ModelContent instance is to call the standard ModelProcessor via ContentProcessorContext.Convert. So it's a bit of a catch-22. The BoneContent class has a constructor but no methods except those inherited from NodeContent... though now (true to form) maybe I've realized the solution by asking the question. Should I create a root NodeContent with two children: one MeshContent and one BoneContent as the root of my skeleton; then pass the root NodeContent to ContentProcessorContext.Convert? Off to try that now...