I haven't seen the final designs from the Defense Distributed project. But my understanding is that even with the almost all 3D printed parts it still requires a lot of putting together, assembly and doing. And even aftera ll that you still don't have a very functional gun. Especially on a low end 3D printer like a RepRap I would be more worried that the gun would blow up in my face. I don't see Defense Distributed as much different than the Anarchist Cookbook ball point pen gun or pipe bomb instructions. Of course that may not be the best comparison since governments don't exactly like the Anarchists Cookbook.