There's no shortage of controversy surround the 3D printing of guns, and there is also no shortage of people designing them. This one, a replica of the infamous Kalashnikov, was designed and printed by Reddit user, EasilyUsed, and it's purely a replica. While this one won't be used to start the next revolution or overthrow any governments, if you're planning to print one out, you can check the laws regarding such toys from Cornell. You can read the whole story here: http://3dprint.com/33946/3d-printed-kalashnikov-toy
Below is a photo of EasilyUsed's finished piece: