The dangers of California's legislation to censor 3D printing

Why would you buy a pipe at Home Depot? A gun barrel is not a firearm, and is not required to be registered or serialized. You can drive to Arizona or Nevada and buy an actual barrel, with rifling, manufactured to meet well-known specifications, without showing an ID. Until this year, you could have a barrel shipped to your California residence without an ID. There's no need to build the Shinzo Abe contraption.

> So my assumption is immediately that some relatively large lobbying group feels threatened by 3d printing, and is using this as a driver to try to control access and limit business impact.

Occam's razor. This isn't a shadowy manufacturing cabal, threatened by 3D printing. Gun control lobbyists are trying to prevent the printing of handgun frames and Glock switches, because they're the easiest parts to print.

> Either way, this is bad legislation.

California legislators haven't met a bad gun law that they don't like.

lots of companies got fat and happy selling you plastic crap for a fortune, now 3d printers let you make plastic crap at home for pennies.

If they must pass these laws, it must include protections for printing consumer goods parts, if they won't add that I will not vote for you.

contact your state reps and tell them that.

Like you say, you just need to build a key metal piece, and voila, the rest is buying parts that can be delivered to you, in some cases fully assembled.

You could also just buy black powder guns directly to your home (idk about in CA or NY though) which are not treated as "firearms" by the ATF.

The only people shooting 3D printed guns are enthusiasts usually, who have other guns.

The barrel will be metal. In designs made for the US market, it will almost certainly be an actual manufactured gun barrel, since gun parts other than the receiver are not closely tracked in the US. In designs for Western Europe, the metal parts will be either milled or things you can buy at the hardware store[1].

The barrel and chamber being made of something tougher than you can get from an FDM machine is basically a requirement for making a gun that doesn't explode in your face when you shoot.

1: Here's an image of all of the parts going into a gun designed to be made in the EU. Per the wikipedia article, the barrel rifling can be added with electrochemical machining https://en.wikipedia.org/wiki/FGC-9#/media/File:FGC-9_Compon...

> what's special about 3d printers?

They can make guns made out of plastic and metal detectors are kind of the primary way we try to find guns on people.

You are probably right about the lobbying group, I agree.

Edit: I'm not saying it makes sense, but this is the angle the congress folks are taking, sheesh.

Any real attempt would need to be at the national level, not that I would advocate for it, but it's simply a pipe dream to create a "gun free zone" in a country with 100s of millions of firearms. There are plenty of gun enthusiasts in California, they just don't flaunt it or talk about it.

I'd say the real groups behind this are the anti-gun ideologues, the "do whatever it takes to stop my panic attacks over Bad Things maybe happening" left-wing control freaks, and the old-fashioned "big state" authoritarian crowd.

And the only reason they're paying attention to 3d printers is that some pro-gun ideologues and provocative makers have been talking up the concept of 3d printing guns.

when you manufacture a personal firearm, it is supposed to be yours, for your use. the 3d printer aspect, makes it possible for a group to print large quantities of receivers, under the radar, to be combined with "accesory parts" close to "drop-in" assembly style.

If they wanted a gate on designs it would have to happen in slicing software, not the actual printer.

Don't laugh, this sort of regulatory capture type crap is exactly where it'll trickle down to if they get what they want for guns.

Louis Rossman also touched on the topic: https://www.youtube.com/watch?v=kS-9ISzMhBM

I've seen more by others but can't recall them all. Without going too far down a conspiracy theory rabbit hole, the momentum for this seems to be coming from a variety of sources:

    * New York being New York and trying to make thinking about guns a thought crime
    * There's European company (forget the name) that makes specialized software that can do this.  They're lobbying so they can inject themselves for some tasty rent seeking.
    * A variety of companies that see right-to-repair (and thus home 3D printers, CNC-milling, etc.) a threat to their bottom lines.
    * General ignorance by our law makers

You would be correct.

https://xcancel.com/2Aupdates/status/2036437116456940001#m

In the US low powerd black powder is super easy to get you don't even have to take fireworks apart or do home lab chemicals stuff.

I mean we're talking about CA, so they kinda already tried to do that

https://giffords.org/lawcenter/state-laws/ammunition-regulat...

But, it may not be constitutional:

https://calmatters.org/justice/2025/07/gun-law-ammunition-ba...

So the real reason is that the ultimate law on the books on gun regulation was written by a band of, you know, armed revolutionaries, who were pretty big fans of the whole armed revolution-ing thing. And it still hasn't been amended.

I bet if you went with a simple majority vote today, you wouldn't get the 2nd amendment. But amendments are pretty difficult to pass, much higher requirements than a simple majority.

If you use the ATFs guidelines on what is considered a prohibited person, it likely applies to about half of all US adults that are prohibited from buying ammunition. This when you consider ~30+% of US has used cannabis/fentanyl/etc or misused a prescription drug in the past year, the insane number of people we've made felons, the fact that restraining orders are now practically part and parcel of divorce negotiations as leverage (permanent restraining order bars you from owning guns), and then the fact that DV convictions are incredibly common in USA (police automatically arrest someone if they show up on a domestic complaint), then add the illegal immigrant population on top of that.

Even though I'd bought multiple firearms in California, this background check always rejected me, probably because my name doesn't fit in their databases. Somewhere between 10% and 16% of legal firearm owners in California are denied ammunition due to this faulty system.

1. https://calwaterfowl.org/navigating-californias-new-ammuniti...

carbon, sulphur, and potassium nitrate, in a particular ratio.

potassium nitrate is watched, and reported in large quantities, or particular form, but can be manufactured by most people that can follow a recipe.

regulating the propellant cant stop it from being made.

also someone really didnt think it through by regulating "receivers"

they regulated what is most often the easiest part to manufacture. the core parts [barrel, bolt, chamber] are difficult to build, require tech to build from stock, and are sold off the shelf, while receiver needs 4473 as if it was a fully functional firearm, and that is the part that can be built, from a 2x4 or a billet of material, depending how long you want it to last.

Happy Patriot's Day this weekend (April 19th)!

Could probably create exceptions for bullets used at the gun range, so you can become proficient and safe.

Tricky part would be hunting, but restricting such a tax to ammo used for handguns is probably an 80% solution.

1. https://everytownsupportfund.org/press/everytown-to-convene-...

https://leginfo.legislature.ca.gov/faces/billTextClient.xhtm...

This is akin to trying to require all image editors to detect currency and refuse to process images of it. Making open source image processing software would probably have to be illegal because end users could trivially modify it to illegally process currency, or having general-purpose computers that can run software the government hasn't approved would need to be banned.

- The problem of counterfeit currency is well acknowledged and has roots in antiquity. Reasonable people agree that currency genuinely cannot do its only job if counterfeiting is possible, and have had that agreement for thousands of years. In addition, the sole right to print currency is given to the US government in its constitution (almost certainly for this reason). These two things grant government control over printing currency both a moral and a legal legitimacy that government control over printing gun parts doesn't have.

- Because the government has control over the design of legitimate currency, it is actually practical to prevent software from reproducing it. See: https://en.wikipedia.org/wiki/EURion_constellation . Gun parts have no such distinguishing characteristic, and cannot be made to have one, since there is no authoritative body responsible for all of them. Having such a marking could be made legally mandatory, but it is not actually required for the function of the part, whereas currency needs to match the authentic design in order to be useful. It is therefore much less practical and effective to mark gun parts to prevent replication than it is to similarly mark currency.

- Creating your own guns specifically (and weapons, generally) is widely seen as a natural or God-given right. I would go so far as to say that it is intrinsically human, and that losing access to it would be as painful to some as losing access to rock 'n roll. I would say that due to this pain, losing that right is one of the chief signs of an enslaved people. While not everyone would agree with me, many would, which gives the issue a divisive moral edge. By contrast, creating your own currency might be seen as some sort of natural right by some people, but creating your own US Dollars certainly is not seen that way by anybody. Well, I'm sure you could find someone, but you know what I mean.

- As far as I know, there is no law compelling printer/photocopier manufacturers to use anti-counterfeiting software, and compliance is voluntary (but apparently pretty widespread -- though I doubt it's universal). A similar voluntary setup with 3D printer manufacturers would be less objectionable (though also much less likely to succeed). Introducing any sort of mandatory compliance regime introduces friction, slows innovation, and invites corruption.

- Manufacturing gun parts is actually pretty easy, and could be accomplished via many methods accessible to hobbyists, ranging from whittling by hand to duct taping hardware together to lost wax casting to desktop CNC to a desktop injection molding setup to metalworking on a lathe in a garage machine shop. It is in no way limited to 3D printing, though that admittedly lowers the bar a bit. Learning to work on guns is not significantly harder than learning to work on cars, though perhaps fewer people know how to do it. Thus, a focus on 3D printing seems much more driven by sensationalism, paranoia, and ignorance of this fact than it is by practical assessment of the issue. By contrast, creating even minimally recognizable counterfeit currency without the assistance of a computer is practically impossible and certainly cost-prohibitive. In manufacturing gun parts, it is perfectly practical in some cases to do the equivalent of drawing a dollar bill with a crayon -- something much less successful in the counterfeiting world.

- Adding broad pattern-recognition controls to a 3d printer is a novel and difficult problem that will likely impact innocent people doing legal things. Preventing the printing of accurate-looking currency has a much more narrow impact, and is much more focused on people doing illegal-adjacent things.

Without meaning any malice toward your question, I mention that I write because you have stepped on one of my pet peeves: it seems to me that an inability to see the difference between things that are, in fact, different, is one of the major failure modes of modern society in general. We need an appreciation for texture and nuance if we are to navigate the world rightly.

In the United States we even have a word for an assault weapon on four legs—pitbulls. Most breed-specific legislation, where it exists, targets pitbulls which are not a single breed nor group of related breeds, but basically any large muscular dog with a short snout and blocky head. The American Pit Bull Terrier is one such breed but far from the only one targeted by BSL.

I think it was Toyotomi Hideyoshi who said something like, the law is not obligated to logic, but it still must be followed.

Most people in California who vote on these matters have not held a BB gun, let alone a semi automatic.

They have 0 idea that you just cannot buy actual guns from a grocery store in California anymore!

They think you can just buy a gun at Walmart like you can buy a can of Coke. I was able to pull up clips made in 2023 and 2025 that were literally claiming that. Hasn't been true since atleast 2009, likely even earlier.

A few years ago a local Walmart was clearing our their air gun and rifle selection after there had been a shooting on the east coast that was all over the news. Since ammo have become really expensive, I bought out the whole shelf of air rifles so I could continue to target practice with a focus on my breathing.

People called the cops on me. Multiple people verbally abused me as a gun nut and recorded me buying them on their phones. I had air guns - *children* *toys*. They thought it was the real deal!

The local sherrif's department received nearly a 100 calls that hour when we spoke. When I asked them why they even bothered to turn up because they know no Walmart in a 300 mile radius have ever sold a rifle in the last 20 years as was described to them over the phone, they just shrugged and said "politics".

California gun laws in a nutshell.

You really don't have to go that far. A very high quality control board (eg. an original Prusa) is like 90$ and cheap ones go for 25$.

You could buy the licensed printer and swap the board. Or maybe even just flash the firmware on the licensed printer

Hey, my printer might be going up in value.

  (Added 2015) Some of the documents that we previously received through FOIA suggested that all major manufacturers of color laser printers entered a secret agreement with governments to ensure that the output of those printers is forensically traceable. Although we still don't know if this is correct, or how subsequent generations of forensic tracking technologies might work, it is probably safest to assume that all modern color laser printers do include some form of tracking information that associates documents with the printer's serial number. (If any manufacturer wishes to go on record with a statement to the contrary, we'll be happy to publish that here.)

  (Added 2017) REMINDER: IT APPEARS LIKELY THAT ALL RECENT COMMERCIAL COLOR LASER PRINTERS PRINT SOME KIND OF FORENSIC TRACKING CODES, NOT NECESSARILY USING YELLOW DOTS. THIS IS TRUE WHETHER OR NOT THOSE CODES ARE VISIBLE TO THE EYE AND WHETHER OR NOT THE PRINTER MODELS ARE LISTED HERE. THIS ALSO INCLUDES THE PRINTERS THAT ARE LISTED HERE AS NOT PRODUCING YELLOW DOTS.

  This list is no longer being updated.

From purely a technical standpoint: the printer indiscriminately adds tracking dots to all documents, the proposed 3D printer regulation requires the printer to phone home and make some dispositive call on what it's allowed to do.