How do they temper the steel in the receiver so the thing doesn’t blow your hand off the first time you try to shoot it?
Mr. Wilson, who runs a Web site called Defense Distributed.
He calls the gun the Wiki Weapon. In a video explaining the project’s goals, he describes the Wiki Weapon as the world’s first “3-D printable personal defense system.”
“What’s great about the Wiki Weapon is it only needs to be lethal once,” Mr. Wilson says in the video, in a monotone voice.
Steel ha ha. Think PLASTIC. What you COULD do is use the plastic in a lost wax process and cast bronze parts so that if they fail it will be by splitting rather than shattering. Wouldn't want to make a ma deuce out of plastic.
Right now the efforts are around the AR15 lower receiver, which is not subject to high pressures - and what they’re making barely even works for that use.
Someday the tempering problem will be solved. It’s just a standard manufacturing problem, which will coincidentally be useful for this application.
Michael Guslick, an amateur gunsmith who has written extensively online about the considerable challenges of 3-D printed guns, said people had been experimenting with homemade guns for some time. He said the most notable example was the zip gun, which is made from off-the-shelf plumbing parts. (Not surprisingly, the schematics and instructions can be downloaded online.)
"This is just applying a different technology to something that is already being done," he said. "But making one on a 3-D printer is a lot of work when your local plumbing department is so close by."
So the bottom line is making a barrel or reciever with any accuracy still requires an experienced machinist....and wait, experienced machinists have ALWAYS been able to make guns.
This shows some 3D printing in impressive metals:
Additive Manufacturing using metals
http://3dprintingsystems.com/additive-manufacturing-using-metals/