I saw a thingy on the Net a while back that someone had linked to.

It was an interview on Alex Jones Info wars. Might be the same guy. This guy was "printing" 30 round AR mags THAT WORKED. They "printed" the mag and follower, and had to use a metal spring.

The first one of these I saw was years ago on the TV. They made a 15" Cresant wrench that worked.