This shop has some nifty 3D shapes that you can make yourself with free and open source software. Each shape has links to the 3D open source software that you could use. If you want them without having to design them yourself, you can buy them from here.
Besides nifty 3D shapes, I specialize in prototyping of medical devices. Medical device parts can be made for very cheap before going into production or even expensive machine shops. This is a very fast and cheap alternative to the former.