1. United States
2. Calif.
3. Letter

I am writing to urge you to oppose AB 2047, which would require all 3D printers sold in California to include a state-certified “firearm blueprint detection algorithm” or be banned from sale after 2029. The bill’s intent is understandable. 3D-printed firearms are a legitimate concern. But the mandate it creates is technically impossible and would effectively destroy consumer 3D printing while doing nothing to prevent illegal manufacturing. 3D printers do not read shapes. They execute G-code: coordinate and movement instructions. No algorithm running on consumer hardware can reliably distinguish a firearm component from an ordinary mechanical part based on that data. To attempt compliance, manufacturers would need to build persistent file-scanning systems into every printer sold, surveillance infrastructure with no technical guardrail keeping it limited to firearms. The EFF has documented that this replicates the lock-in seen with 2D printer ink DRM, benefiting incumbent industrial manufacturers at the direct expense of smaller competitors, open-source projects, and consumers. The practical result: a $300 hobbyist printer becomes a $1,000+ locked appliance, if available at all. The 1.5 million California students who use 3D printers daily lose access to affordable tools. And anyone intent on printing illegal firearms simply uses pre-2029 hardware or crosses state lines. I urge you to: • Vote no on AB 2047 in Appropriations. • Request a technical feasibility assessment from an independent body before any further vote. • Require the author to identify a single jurisdiction where comparable print-blocking technology has worked as intended. • Redirect enforcement to California’s existing ghost gun statutes, which already address unlicensed firearm manufacture.