I recently read an article in Wired Magazine that featured a DIY enthusiast who is also a model train hobbyist. He began to wonder if it was possible to use 3-D software to create scenery accessories for his railroad. He began to design miniature trucks, trains, bridges, etc that he could use to enhance his railroad model. Utilizing a company called Shapeways, he was able to upload his design files to their site and they would print his model and ship it back to him. He now sells his models on the site for a little extra income!
Check out shapeways.com. Not only can you buy and sell 3d objects that people have designed, you can also upload and print objects of your own!