

For a printer to be compliant, it mustn’t be possible to bypass the restrictions. So your printer might not even be legal if it allows you to flash custom firmware.
identify and reject print requests for firearms or illegal firearm parts with a high degree of reliability and cannot be overridden or otherwise defeated by a user with significant technical skill.





I think you missed the part where it said “[…] cannot be overridden or otherwise defeated by a user with significant technical skill.” I.e. either the printer will only allow flashing with signed firmware containing the detection algorithms, or it would have to be done by a separate chip which isn’t affected by flashing firmwares.
But also detecting firearms in gcode is a ridiculously complex task, and if companies actually try to comply they might opt for building the algorithms into their closed source slicer instead, and then only allowing their printer to print encrypted/signed gcode. Or they might do the analysis using some AI algorithm on their cloud servers, requiring an always on internet connection to print things. It might be tempting to think that nobody would buy a printer like that, but I think that enough people will do if they make it convenient and cheap enough.