California’s new bill requires DOJ-approved 3D printers that report on themselves targeting general-purpose machines.
Assembly Member Bauer-Kahan introduced AB-2047, the “California Firearm Printing Prevention Act,” on February 17th. The bill would ban the sale or transfer of any 3D printer in California unless it appears on a state-maintained roster of approved makes and models… certified by the Department of Justice as equipped with “firearm blocking technology.” Manufacturers would need to submit attestations for every make and model. The DOJ would publish a list. If your printer isn’t on the list by March 1, 2029, it can’t be sold. In addition, knowingly disabling or circumventing the blocking software is a misdemeanor.


“3d printing guns” isn’t about the pressure holding parts, it’s about the traceable serial number holding parts. On most firearms the “lower assembly” or “receiver” (frame, trigger group, feeding assy) is legally considered the firearm and is what bears the serial. Most of those can be printed and use off the shelf hardware to work, albeit with a much lower lifespan.
Pressure containing wear parts that are meant to be exchanged (barrel and breech bolt) typically do not carry serials and are thus not normally traceable. If you eliminate the serialized, traceable part of the firearm, then any collection of parts could be used.
That said, eliminating an entire hobby and industry because gun serialization laws haven’t been updated in a hundred years is probably not the right way to do it.
Is printing a lower less illegal than removing the serial number? Must be, otherwise what’s the point other than cost?
Yes. In most of the US removing a serial is explicitly illegal, while manufacturing a firearm for personal use (the serialized part is legally the firearm, but most places don’t require you to serialize personally manufactured firearms) is completely legal.
I believe it’s a federal felony to remove the serial.