[Haddit]

I have a 3D printer and I’m about ready to open up a store at one of these places.

A designer makes a 3D part and uploads a STL file. If someone sees it and likes it, he can download the file and print it, or he can have the part made and shipped to him. I.Materialise creates parts in 17 different materials.

http://cubify.com/

http://www.shapeways.com/

http://i.materialise.com/

http://www.thingiverse.com/

[CodeToad]

I am not sure the viability yet of this only because it is so new, but I see the vast potential as nothing short of amazing, stunningly revolutionary. The opportunities are endless. Good luck! I mean it. I hope you come up with some great ideas how to capitalize on it.

[Myrddin]

3D printing as a service seems a reasonable line of business. A bit like the old shops that take your photographic film and make prints. There may be similar obstacles in terms of what the printer can legally print. The high end machines are really too big of an investment for an individual. There is little payback for the investment unless you can keep the machine occupied doing things that repay the purchase and operation cost.