About this 3D model
This is an extension for the legs from the first footed vertex. If you haven't printed them yet, use the mod3 footed vertex. It's longer and doesn't need these extensions. You can see these in use in this video: http://www.youtube.com/watch?v=KkMdNJBVHiI&context=C3167214ADOEgsToPDskKMJbI2bxfjvqHBwX56U9ED