Here's a very detailed article on the subject. http://www.law.ed.ac.uk/ahrc/script-ed/vol7-1/bradshaw.asp

Come to think of it, I'll go ahead and submit it on its own.

You might enjoy Cory Doctrow's Print Crime[1] which centers on this exact topic.

[1]: http://craphound.com/?p=573

Also Bruce Sterling's Kiosk:

http://web.archive.org/web/20080115084153/http://www.sfsite....

3D printing of metal is here, if expensive. With that technology in mind, a computer-file gives you the ability to print a specially shaped piece of metal. A piece of metal that turns your legally owned firearm, and turns it into a fully-automatic cop killer that mows down entire preschools.

By the time that idea is exposed to mainstream society, hopefully society's knee-jerk response won't damn the entire industry. (The fact that the piece of metal is easily made today doesn't escape me. Society, however, is not known for acting rationally in response to danger, especially to children.)

"You wouldn't download a car"

Yes. Yes I would.

If I could download a car, I'd certainly do it because that would mean that production cost is basically zero.

Wait till you see what the toner cartridges are going to cost you.

Soon enough we'll find out if most people _would_ 'steal' a car.