By a Demonrat. What a surprise!
New York congressman Steve Israel wants to ban "undetectable" 3D printed guns.
Yet another law in search of a problem. For criminals, stolen or black market conventional guns are ever so much easier and cheaper to obtain, and a few orders of magnitude more reliable.
As far as "undetectable" goes, so far I haven't seen a printed gun that does not have at least the chamber and barrel made of metal. A fully composite gun today might be good for a couple shots before the barrel melted. Perhaps someday we will be able to print ceramics suitable for gun barrel pressures, but not in the near future.