You cannot fully 3d print an effective firearm on a consumer 3d printer. When people talk about 3d printing a gun they are almost always talking about 3d printing a single part—the lower receiver. Federal law considers the lower receiver to be a gun, and it is the part with a serial number.

A lower receiver is not complicated. It essentially just a quirk of the law that the ability to 3d print a lower receiver is useful to people who want to manufacture “untraceable” guns.

You could change the law so that barrels have to have serial numbers and accomplish nearly the exact same thing as completely banning 3d printers.

Also buying a kit, 3d printing a lower receiver, snd assembling an effective firearm is about as difficult as buying a kit to assemble an 3d printer and using existing open source slicers (or modifying a 3d printer to let you use an open source slicer).

And if 3d printers are as dangerous as the proponents of this legislation thinks they are, people would just hop across the border to Nevada and use a 3d printer there.