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.
You don't print the explody bits; you have to purchase things like the barrel and the trigger assembly.
However, I know an engineer at Sig Sauer who printed his own gun and he's never fired it while holding it…so, still prone to eventual catastrophic failure ¯\_(ツ)_/¯
At that point though, you may as well start regulating the purchase of lumber, since it sounds like you could just as easily make the printed components in a basic workshop as with a 3d printer
I suppose technically you could but it would be a hell of a lot of work and you'd need detailed drawings.
The 3d model already has all of the geometry and hole locations required from the manufacturer.
If you know your printer well, all you do is download the model, slice it and press play.
If you have the 3d model, you already have the drawings. Quite literally. Just need to print off some views with measurements, if you want it on paper, otherwise, use the CAD model and get measurements as needed.
At that point, it's just down to having the tools, skills, and material. Someone with good skills, tools, and material could make the equivalent parts faster and of better quality than a bed-slinger. Someone without the skills… well, they'll probably have time to build the skills in the process.
Now, when it comes to materials, I think that there's definite risk there. Wood often exhibits worse shear strength along its grain than well-tuned printers do along layers (a good example of this weakness can be seen in the rear totes of old Stanley-Bailey bench planes - it is a minority of them that have not sheared where the handle meets the mounting section). So, that has to be taken into account in laying out the part in the raw material.
Everything will fail eventually, the question is how long it will take and more importantly if the failure can be predicted.