A [1]proposed California bill would require 3D printer makers to use state-certified software to detect and block files for gun parts, but advocates at the Electronic Frontier Foundation (EFF) say it would be easy to evade and [2]could lead to widespread surveillance of users' printing activity . The Register reports:

> The bill in question is [3]AB 2047 , the scope of which, on paper, appears strict. The primary goal is clear and simple: to require 3D printer manufacturers to use a state-certified algorithm that checks digital design files for firearm components and blocks print jobs that would produce prohibited parts. [...] Cliff Braun and Rory Mir, who respectively work in policy and tech community engagement at the EFF, claim that the proposals in California are technically infeasible and in practice will lead to consumer surveillance.

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> In a series of [4]blog posts published this month, the pair argued that print-blocking technology -- proposals for which have also surfaced in states including New York and Washington - cannot work for a range of technical reasons. They argued that because 3D printers and other types of computer numerical control (CNC) machines are fairly simple, with much of their brains coming from the computer-aided manufacturing (CAM) software -- or slicer software -- to which they are linked, the bill would establish legal and illegal software. Proprietary software will likely become the de facto option, leaving open source alternatives to rot.

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> "Under these proposed laws, manufacturers of consumer 3D printers must ensure their printers only work with their software, and implement firearm detection algorithms on either the printer itself or in a slicer software," wrote Braun earlier this month. "These algorithms must detect firearm files using a maintained database of existing models. Vendors of printers must then verify that printers are on the allow-list maintained by the state before they can offer them for sale. Owners of printers will be guilty of a crime if they circumvent these intrusive scanning procedures or load alternative software, which they might do because their printer manufacturer ends support."

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> Braun also argued that it would be trivial for anyone who uses 3D printers to make small tweaks to either the visual models of firearms parts, or the machine instructions (G-code) generated from those models, to evade detection. Mir further argued that the bill offers no guardrails to keep this "constantly expanding blacklist" limited to firearm-related designs. In his view, there is a clear risk that this approach will creep into other forms of alleged unlawful activity, such as copyright infringement. [...] Braun and Mir have a list of other arguments against the bill. They say the algorithms are more than likely to lead to false positives, which will prevent good-faith users from using their hardware. Many 3D printer owners also have no interest in printing firearm components. Most simply want the freedom to print trinkets and spare parts while others use them to print various items and sell them as an income stream.



[1] https://hardware.slashdot.org/story/26/02/19/2219256/californias-new-bill-requires-doj-approved-3d-printers-that-report-on-themselves

[2] https://www.theregister.com/2026/04/14/eff_california_3dprinted_firearms/

[3] https://leginfo.legislature.ca.gov/faces/billTextClient.xhtml?bill_id=202520260AB2047

[4] https://www.eff.org/deeplinks/2026/04/dangers-californias-legislation-censor-3d-printing