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.
All US firearms purchases made at gun stores involve background checks. In some states (like California) you are also required to do so for private party sales (like buying from your neighbor).