Cody Wilson, a law student at the University of Texas, is in the process of building a completely functional printed gun. “We hope to have this fully tested and put the files online in the next couple of months,” said 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. “We will have the reality of a weapons system that can be printed out from your desk. Anywhere there is a computer, there is a weapon.”