Red Hel.

I'm not going to pretend I understand 3D models, but from what I gather, you design something, in 3D and it is then created by machine in the material of your choice. It is "an additive manufacturing process whereby one machine turns a digital file into a finished physical object by building up that object layer by layer."
Or something.
Anyway, Shapeways is a site where you can go, view various renderings, and sometimes pictures of finished pieces, and order them for yourself. It seems as though you can also design your own things on there as well as collaborate with designers on custom pieces.
I've only looked at jewelry but they have lots of different categories.