... Silly people; any kid can make a zip gun although appropriate antennas are getting harder to find; and anyone competent with hand tools can make a WW2 era sub-machine gun; even without 3D printing.
Once the knowledge is out in the wild untraceable fire arms are just a matter of desire, time, knowledge and effort; and I am not counting the spare parts sources that let any untalented, non fabricator assemble firearms (note; a FFL (federal firearms license) is needed to legally purchase a frame (with a serial number).
Use your intellect not your emotions... "You can't put the genii back in the bottle."
Enjoy!