Not too long ago, the gun control advocates were going a little ape-shit over the ability of 3D printers to make AR-15 lower receivers. Although the printers were able to produce some lower receivers of moderate quality capable of firing several hundred rounds, they were still plagued by stress fractures and eventual damage. Not anymore, the Defense Distributed group has announced the availability of a personal, in-home, CNC mill designed to mill an AR-15 lower receiver from metal for the low cost of $1200. Federal law permits citizens to construct their own weapons for personal use without licenses as long as they do not sell them which means people can 3D print a receiver and then mail order the remaining parts. Voila! For about $2000, anyone can have an unregistered, untraceable "ghost" AR-15. This isn't the first 3D printed metal weapon, there are already 3D models and printers capable of producing a complete 1911 .45 as well.