Print your gun parts at home.

• Author: Tuccille, J.D.
• Position: Artifact - Brief article

IN FEBRUARY, the techie gun-rights group Defense Distributed unveiled a 3D-printed lower receiver for an AR-15 rifle that withstood hundreds of rounds of fire. A YouTube video of the component in action was accompanied by the terse statement, "Does not fail from firing stresses. 600+ rounds."

This impressive development came just months after the group earned some ribbing for its first attempt at a homebrewed plastic receiver (the core of the AR-15 and the component that is technically regulated by law), which disintegrated after six shots. But success followed failure, as Defense Distributed unveiled a high-capacity rifle magazine that could be manufactured in a home workshop on a 3D printer. They named it Cuomo after NewYork's governor, who recently pushed a new, stricter magazine limit through the state legislature.

3D printers, which...