California law requires firearm-blocking tech in new 3D printers once ASTM standard exists
California has signed into law a bill requiring 3D printer manufacturers to build firearm-blocking technology into their machines, but only once ASTM International publishes an industry standard defining what that technology looks like. No such standard exists yet.
The law makes California the second state to pass firearm restrictions on 3D printers, after New York. Colorado and Washington have similar bills moving through their legislatures.
Existing printers are exempt; the rule only applies to machines sold after the mandate takes effect, and it doesn’t touch ownership or use, only sale and transfer. The California DOJ must check quarterly for a published ASTM standard starting no later than July 1, 2027, and that obligation ends July 1, 2029. If ASTM hasn’t published anything by then, the DOJ is no longer required to keep checking, which means the rule could simply never activate.
Tom’s Hardware lays out why that’s a real possibility: the two known approaches to blocking firearm files, matching against a known gun-file database or running a trained model to flag suspicious geometry, both have documented failure modes. A database match breaks if someone resizes the file or splits it into multiple printed pieces assembled later. A detection model risks false positives on parts that resemble gun components but aren’t, like barrels, brackets, levers, or tubes used in legitimate hardware.
The Electronic Frontier Foundation said in June 2026, as quoted by Tom’s Hardware, “there is no world where the mandated technology actually works as intended.” California’s law tries to sidestep that criticism by deferring the technical definition to ASTM rather than having the DOJ write its own spec, which is also the mechanism that could leave the mandate permanently unenforced if the standards body never acts.