I understand the intent, but feel that there are so many other loopholes that put much worse weapons on the street than a printer. Besides, my prints can barely sustain normal use, much less a bullet being fired from them. I would think that this is more of a risk to the person holding the gun than who it's pointing at.
It doesn't have to be from gun manufacturers. Any manufacturer can go to the politician they own and say "People are making open source versions of our highest profit margin widget, find a way to make it stop." Then politician says, "Well, New Yorkers want more gun laws, we can abuse that…"