I think it's interesting to note that not only is there precedent for this type of "blocking technology that prevents the printing of certain things"[1], but it's also inconsequential and uncontroversial enough that most of the people here obviously have never even heard of it.

We lost the ability to print $50 bills with our HPs[2] and it had no noticeable negative impact on society. I'm not sure why losing the ability to print a gun with our Prusas will be any different.

[1] - https://www.scienceabc.com/eyeopeners/cant-photocopy-scan-cu...

[2] - https://h30434.www3.hp.com/t5/Printers-Archive-Read-Only/Won...

Images of authentic $50 bills are pretty easily detected. They are designed that way.

It's not technically possible to detect "gun geometry".

The only way to comply with this law is to ban 3d printers entirely.

Other people have already pointed out the differences between implementing a check for a specific banned print and a vague categorical ban. It would be like if printer manufacturers weren't just asked to prevent the printing of US dollars, but anything that looks like money, having an ability to detect if something is money-like based on look and feel alone, without relying on an existing database or hardcoded watermarks.

Your implication makes me think that you assume that this useful-yet-not-overreaching detection tech is possible. Do you have any ideas for how this would be implemented? Because in my mind, the only way to ensure compliance would be either a manual check (uplink to the manufacturer or relevant government authority, where an employee or a model trained on known gun models tries to estimate the probability of a print being part of a gun) or a deterministic algorithm that makes blanket bans on anything remotely gun-like (pipe-like parts, parts where any mechanical action is similar to anything that could be in a gun). These scenarios seem to be both a lot more annoying and a lot more invasive. There's no negative consequences for tuning detection to always err on the side of caution and flood the user with false-positive refusals to print. Both scenarios are obviously a lot more involved and complicated than a basic algorithm checking if you're trying to print an image of a US dollar. Therefore I don't see a reason why drawing this comparison is useful. The only thing these implementations have in common is that they're detecting something.

I was bounced out of a Kinkos circa 2000 with my grandparents for attempt to counterfeit Pokémon cards on the photocopier. Mind you I didn’t seek to make illegal copies. I just wanted to photocopy and color in and draw on my own artistic creations. Fun times learning about copyright mechanisms and fraud as a kindergartner.

The problem is that images of $50 bills have enough alignment marks that the code to detect them could run on hardware from the ‘90s. From what I’ve seen, these bills naively assume that somehow the printer has to detect whether something is a gun or part of a gun. The fact that slicer software has to transform a mesh into gcode for a specific printer and specific settings means that a printer can’t just hash the file or something to check a blacklist. And how do you tell if something is part of a gun? A PVC pipe could be a gun barrel by that metric. Or maybe a trigger assembly is designed for a rubber band gun instead of an illegal firearm.

https://xkcd.com/1425/

I doubt there is a weapons expert that could look at a given STL file and unambiguously tell you whether something was “part of a gun” or not. If these laws pass, they will be either unenforceable, effectively ban all 3D printer sales due to the immense difficulty of compliance, or worse, be another avenue for selective enforcement.

Furthermore, the whole “ghost guns” thing is entirely overblown and misunderstood by people who have never seen or used a 3D printer except in the movies, where Hollywood has latched onto the idea that they are designed primarily for making guns. A consumer grade 3D printer is going to print a gun that will explode in your hands the first time you try to use it, if any of the meaningful parts of the gun are printed. And nothing is stopping people from say, fabricating gun stocks with a table saw and router, or building a gun out of hardware store parts. Why aren’t we also banning mills and lathes while we’re at it? There are also chemicals at a hardware store that could be used to make explosives. If the concern was really “making guns at home”, we’d outlaw Ace Hardware and Home Depot.

Counterfeiting money is bad, and should be illegal (the wisdom of forcing such software into printers notwithstanding). Manufacturing your own products is good, and shouldn't be illegal.

But this tech isn't required by law, is it? You can legally make your own printer without a $50 bill detector.

Uh, I'd say that something has in fact been lost in that every single printer sold watermarks every document printed regardless of if you are attempting to print a $50 bill or not.

There are plenty of people who change their behavior because that tracking is in place, regardless of if what they are doing (or would be doing) is in any way illegal.

Terrible example IMO.