I don't really get the big fuss about the printed gun that's been doing the rounds on news websites lately...
Obviously the 3D printer is unable to produce the complex parts of a handgun... Clearly it can't just print gunpowder for you, or a mechanical part such as a spring... it can only print the 'static' parts like the outer casing, handle, barrel etc.
In that sense, we have always been able to make a home-made gun - all the 3d printer has achieved is to speed up / automate that process..
But 3D-printer or not, with a little bit of material (sheet metal, balsa wood, fibreglass, plastic or wateva) some basic tools and a whole lot of dedication, one could always produce the static 'chassis' that makes up a handgun.