I took the "Basic Platform Slipper" and added a giant platform to the shoe to it and it's awesome. It fits great and the doll can even stand in it!
If you print this PLEASE tell me so I can gloat with my daughter about it! :-D
Also, this is my only my second attempt at doing 3d modeling (the "ballet flat" / "basic slipper" was the first) so if you have any suggestions or tips, I'm all ears.