3D printing can produce a whole helluvalot of cool things, but at the end of the day, it's just plastic. Guns are not meant to be made of plastic. If you make them of plastic, they break. And then the gun explodes in your face, leading to a rather complicated explanation at the hospital as to how you got plastic embedded in your forehead.

The ambitious 3-D printing gunsmiths behind the Wiki Weapons project created the lower receiver (the bit of the gun that holds most of the important moving parts) of an AR-15 carbine out of plastic, and then bolted it onto an otherwise perfectly functional rifle. They didn't expect it to work. In the words of the project leader, "we knew it would break".

So, armed with the knowledge that they were playing with a ridiculously unsafe firearm, how did they choose to test it? In a Mythbusters-style bunker, cowering behind protective screens? No, they did what any self-respecting plastic-gun-maker does and went down to the range and shot it. Not even any safety glasses. Unsurprisingly, the plastic gun broke in half after just 6 shots -- they're just lucky that they escaped with their eyesight intact.

Has this deterred our intrepid wannabe engineers? Not even slightly. They say they're gonna be back, with a new and improved design, so make sure you steer clear of . On the upside, we might get a good new entry for this year's Darwin Awards. [Defence Distributed via Wired]