You need to find someone with a 3D CNC hot wire foam cutter. While there's not one in every garage, they're not all that uncommon. A friend, a farmer, about 1/2 mile away has one and I hear there's a few more around the area. It's not a real complicated tool. Basically the hot wire is pulled through the foam while it [the wire] is moved up and down cutting variable thickness slab from the block of foam. Then the block is rotated, either slightly or a lot depending, and another slab is cut. Repeat until you have a rough sculpture of whatever it is you want. Then smooth it all out with files and sandpaper.. Not rocket surgery.
Anyway, once you find someone with one, they can cut a pair of skates from a block of foam, [ala Styrofoam]. in the case of something reasonably complex like skates, it might take more than one piece, all glued together.The end product can be any size you fancy. Once the foam core is created, there's a variety of methods to finish it. Plaster, epoxy, paint, to name a few.