I agree. Ban all terrorists. Forbid them from getting their hands on any 3D technology.
Oh, right, these laws only affect law abiding citizens who are no threat. They are the ones who will have their hands tied.
Ahh well, it is said that one can not actually complete an average day now without committing at least one felony. What's one more?
Ban politicians. At least ban the ones with stupid mindsets, like that NY congressman Steve Israel. He really thinks criminals and terrorists will go through the trouble of 3D printing, when they can easily buy guns on the black market? Oh, it's about plastic guns. Well, some terrorists caused some major mayhem with some box cutters, yet they haven't banned the manufacture, sale, or possession of those box cutters.
As you say, ban all terrorists. But the lawmakers, enforcers, and jailers seem hell-bent on ignoring them and going after law-abiding citizens instead. Stupid politicians.