Today is a day full with news about 3d printed guns. After article about first commercially available 3d printed metal rifle part I saw this video on Google+ stream. Looks like 3d printed weapons are evolving very fast. Who knows what future will hold ...
From video description:
This is a fully 3D printed rifle I designed. I call it The Grizzly after the Canadian built Sherman Tanks of WWII. It is a single shot .22LR incorporating the coiled mainsprings of the Liberator by Defence Distributed. Like the Liberator the only metal is a 1" roofing nail.
In this first test it fired off a Winchester Dynapoint but the barrel split along both sides for about 2" and the top of the receiver split the same amount.