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Thingiverse Cracks Down on Firearm Parts

3D Printing & Imaging
Thingiverse Cracks Down on Firearm Parts

3D-printed AR-15 lower receiver

This is the lower receiver of an AR-15 rifle, printed in fused plastic filament from a digital model that was, until this week, freely available for download on Thingiverse.

This part is significant because all other parts of the common rifle can be readily purchased in the open market.  A person who builds a working lower receiver has, in the eyes of the state, essentially built a working AR-15. It is legal to do so for personal use (at least under US law), but until lately the required tools, time, and talent put the project beyond the reach of most casual tinkerers.

The rise of desktop manufacturing, however, may be set to change all that. Recently, a 3D printed AR-15 lower receiver made of fused plastic filament was demonstrated to fire and cycle six times before breaking.

Andy Greenberg over at Forbes has the story on the removal of this model, and other key firearms-related physibles, from Thingiverse.  As of this writing, no official statement appears on either MakerBot’s or Thingiverse’s sites, though the action seems entirely consistent with Thingiverse’s established Terms of Use, which were updated following the the site’s first firearms controversy back in 2011 to include proscriptions against content that “contributes to the creation of weapons.”

Up to now, however, the policy has gone largely unenforced.

3D-Printing Firm Makerbot Cracks Down On Printable Gun Designs

100 thoughts on “Thingiverse Cracks Down on Firearm Parts

  1. Math Campbell says:

    Get used to it. As we head towards the fabled dawn of makers everywhere – nanofabrication – we’re going to see censoring a lot more. Imagine a machine that can fabricate ANY material design in hours, perfectly, down to the atom, from a simple feed of elemental molecules. Sure, they’d mostly be the non-metallic elements, at least to start with, but with that comes diamonds and other carbon-based structures, that can conduct electricity and heat, and exhibit magnetism etc.
    At that point, gun-parts are not your concern. Stopping someone building a plague of microscopic hunter-killer robots is more the problem.

    1. Alan Chunkster says:

      Life will be cheap in the future. Sad but true.

  2. FredB says:

    Oh, well. Makers will just have to make do with hand tools, lathes, and mills to make guns as they have for four hundred years.

    1. davidcdean says:

      Of course, but even so, people will continue working on 3d printed receivers. And they’ll continue sharing their work like they do with everything else. Those makers will just cut Thingiverse out of the loop, as many have already done for other reasons.

      Thingiverse did something dumb where they had an opportunity to handle it well, but let’s not pretend this is any more than a minor annoyance for people working on what they want to work on. At least, not from the practical perspective.

  3. Sean Ragan says:

    I note, as an aside, that it just took me about 3 minutes to nab a torrent containing digital models of an AR-15 lower (and the parts for a 5-round magazine) from The Pirate Bay’s “physibles” section.

  4. chuck says:

    There has been a lot of knee jerk reactions lately calling for more bans and regulations. While the root causes of violence run deeper than access to weapons, emotions are running high and guns with macho sounding names are an easy target. Of all the cool and functional things you can do with the technology, guns that break after 6 rounds are pretty low on the list. Thingivarse is a flagship of sorts for 3D fabrication and the maker movement in general. If it reflects badly on us and doesn’t really work anyway, then removing the files is really a non-issue. This is not the time to sulley our reputation by fanning the imaginary fears of psychotic criminal armies carrying plastic death machines.
    Plus, as Sean noted, there’s always TPB- they are awesome.

    1. mark says:

      amen brother!

    2. Robert says:

      “While the root causes of violence run deeper than access to weapons”

      However weapons make it a whole lot easier to express that violence at will.

      “Guns don’t kill people. People kill people. At least, if they’ve got a gun, they do.”

      1. Tommy Gunn says:

        Guns don’t kill people. People kill people … with guns. People kill even more people with semi automatic or automatic weapons.

        Either we live in a society and agree to the rules of that society or we dump the rule of law and it’s every person for themselves.

        1. kjenkinsaf says:

          Violent crime surges in the absence of firearms. Empirical evidence is everywhere (if you don’t get your information from the Brady Foundation). Criminals love a victim unable to defend him/herself. The only way the “rule of law” will stop criminals bent on mayhem is if you were standing by with a ton of them to drop on his head. Whereas I can carry 16 rounds of death on my hip to stop him. Which is more practical? The removal of the AR receiver only makes it harder for people with a valid curiosity to tinker. Nowhere has there EVER been an assault made with a plastic semi-automatic rifle. You are more likely to be injured by the jerking knees than by any firearm.

          1. Blahdro says:

            Yeah, up here in Canada, why we get robbed and shot on the street every day. I myself got robbed and shot three times on the way to work this morning because I didn’t have a firearm!

            Oh wait, I didn’t. Gun-related crimes, home invasions, etc. here are mostly targetted, usually the person being shot is known to the shooter(s) so there are pre-existing relationships increasing the likelihood of violent encounters between attacker and victim. I have never personally known an individual who was shot in Canada because I DON’T HANG OUT WITH CRIMINALS.

      2. LewM says:

        or a bomb, or a baseball bat, or a boot, or a…

        1. Eric P. says:

          Killed a lot of people with a boot have you? I’m guessing that The kid who shot up that movie theater would have scored 0 (ZERO) victims if he went after them with a Doc Martin and I'[m betting you that ALL of the kids and adults who died at the Sandy Hill school would be home today if the attacker had tried to stomp 27 people to death. Seriously, if you are going to trot out false equivalencies stop at bombs – the footwear makes you sound delusional.

  5. Chris Norman says:

    this is absurd why would you think it printing a plastic lower AR receiver is any different then buy a plastic toy gun. these 3d printed plastic toy gun lower receivers are not working weapons they do not contain the mechanism including the triggerrecoil springs and other intricate parts required to make this part functional.

    Additionally I, as an engineer, with a long background in manufacturing I am really tired of the negative publicity that is being promoted around 3 D printing creating weapons. If you want to make a real working lower receiver simply go buy yourself an 8000 dollar mini mill and machine 1 from Bill its stock then you’ll have a real product not a toy.

    3d printers are nothing more then a piece of industrial equipment no different than a milling machine an injection molding machine or anything else and for the most part by and large they are incapable I producing truly functional parts out of Engineering grade thermoplastics especiallythe hobby grade units. I mention this because every month when I read popular science and Popular Mechanics magazines there is a ad in the back of the magazine in the classified section for an 8000 dollar mini mail and the man in the photo is holding a gun part made on the machine. You’ll be hard pressed to find an 8000 dollar 3 D printer that can make a mechanical parts out of machine steel or aluminum that can really be used to make a gun.

    1. FredB says:

      Plastic toy guns get kids expelled from school. Drawing a gun gets kids expelled from school.

  6. R Buchman says:

    I had a handy item removed for violating their TOS. Apparently it counted as ‘gun parts’. If they removed that then I expect my shotshell holders (which help in skeet and trap shooting – an Olympic sport by the way) will be gone soon too.

    In fact if they DON’T remove my shotshell holders, then why the heck did they call my other ammo holder a gun part?

    I admit I somewhat cynically think it has more to do with not wanting thingiverse to be ‘tainted’ by someone searching for “AR-15” and coming up with any matches.

    You know, actually I was curious enough about that after typing it to do some test searches.

    “AR-15” comes up with some matches but none of them are even remotely firearms-related. That was not always the case.

    “shotgun”, “shotshell”, “12 gauge” all have several firearms-related matches. Nothing scrubbed there.

    Maybe it’s just in progress and hasn’t finished yet.

  7. clark brock says:


  8. clark brock says:

    Not every one that gets or makes a gun is going to break the law!

      1. Sean Ragan says:

        I don’t necessarily disagree with you, but quips are a poor substitute for arguments, especially where policy matters are concerned. We get enough jokes and one-liners from TV; one of the greatest things about the internet is that it gives us room to engage in serious, rational discourse about such things instead of simply trading sound-bites.

        If the drug war has taught us anything, it’s that making a commodity illegal does not get rid of it–it just creates a black market and makes it more expensive. Because a pro-gun rights stance is often associated with the political right, I often take a kind of slightly perverse delight in advancing the alternative far-left, radical, militant argument against gun control, to wit: If you make guns illegal, only the rich, enfranchised, and powerful will have them. Even if making, selling, and owning all firearms were made illegal tomorrow, you think Dick Cheney would be cleaning out his gun cabinet and handing them over?

        The argument against the drug analogy, i.e. that drugs are physiologically and psychologically rewarding (or addictive) in a way that guns are not, may have some truth to it, but even the most serious gun control advocates can’t really believe that making guns illegal to make, sell, or possess is, by itself, going to entirely get rid of them. I suppose a radical reduction in their prevalence might be possible if a hugely generous buy-back program were instituted, in which the government offered to buy private firearms from citizens at well above their current market values. But it will be expensive, and there will still be plenty of holdouts, especially among the wealthy for whom cash-in-hand is less of an incentive to part with the family heirlooms or the survivalist stockpile.

        The underpinning of U.S. gun culture is distrust for the government, and not just our current government, or any particular government, but for governments in general. This is an attitude that goes back at least as far as the American Revolution: We want to own guns because we want to reserve the power, in the citizenry, to overthrow the government if it exceeds its mandate. There’s a lot to complain about in the way that the U.S. government works today, but you won’t find many folks who think that’s likely to happen anytime soon (and even fewer who would actually advocate it), but the actual step of handing over our guns is essentially irreversible. I dislike hunting and gun culture in general, but I understand the feeling that giving up our firearms to the government would be a terrible betrayal of our history and our values.

        1. Libertarian Lurker says:

          Good comment Sean, thank you.

          If I could just comment on one thing. Some might read “revolution” and think of citizens marching en masse committing aggression. That is not how it works, witness the failure of the French Revolution. Real change grows on the basis of true ideas, not violence.

          An armed citizenry is still essential though: As more and more people find the truth, they withdraw their consent from those in power. This leads the oppressors to increasingly desperate acts against the people. An armed citizenry serves as a restraint against the worst abuses of a dying regime.

          So, gun rights advocates don’t need to concede the moral high ground, as claimed by the gun grabbers.

        2. Alan Chunkster says:

          Good post. I will add-

          In a world where you can be sure that no l;aw-abiding citizen will be able to shoot you, what is the value of a device that allows you to rob any one of them you see? Thousands. It’s not so high now, for obvious reasons.

          The only difference between a critical thinker and a gun ban proponent is being mistaken about how easy it would be to smuggle or manufacture guns. I’ve had people tell me they can only be made in “factories”, so a ban would work. Even if this were true, wouldn’t the Mexican cartels be happy to build factories? We can’t keep them from CHEAPLY getting cocaine all the way into Canada, there’s no reason they couldn’t get massive amounts of guns into the US once the black market price skyrockets.

          Anything with this high of a markup WILL be sold, no matter what the government does. If we could un-invent guns, perhaps society would be a bette place. (Perhaps not, people sure as dang killed each other with melee weapons back in the day. Perhaps the murder rate is lower now? That’s a whole nother debate.) But un-inventing things is impossible.

          Our non-gun murder rate is higher than most of the developed world’s total murders. I’ve had people tell me these deaths are also due to guns, oddly. Yet other societies with heavy gun-culture don’t have these non-gun homicides, and in some cases, they don’t have the gun homicides, either. I realize most of these countries have heavy regulations, but why favor banning something if regulation might acheive the desired result?

          Lastly- what does a meth manufacturer have when they’re through making meth and have hidden or sold their crop? A meth lab, full of residue. What does a gun manufacturer have when they’ve hidden or sold their illegal guns? A garage. If we can’t stop people from making meth, very cheaply…

      2. Alan Chunkster says:

        If guns are only good for killing people, why does it take 25,000 of them just to kill one person? I think this industry needs some innovation.

  9. mark says:

    The definition of a criminal is one who does not follow the law. What then is the point of creating rules and laws to try and control gun ownership? If someone wants a gun, they will be able to find one if they want it badly enough. Its not as though making guns illegal will mean that all of the guns will simply disappear.

    1. Robert says:

      And yet countries with stricter gun laws have massively lower rates of shootings.

      1. foobar says:

        or not. Gun deaths per 100,000 are about the same in the UK and US, despite the huge disparity in gun ownership.

        1. Alan Dove says:

          US: 10.2 gun deaths/100,000
          UK: 0.25 gun deaths/100,000

          What, exactly, is your definition of “about the same?”

          1. Alan Chunkster says:

            Yeah, we are way higher than Britain… maybe he meant adjusted for guns per capita?

      2. kjenkinsaf says:

        And ridiculously higher rates of murder by knife, rape at knife point, robberies with knives and baseball bats. Burglary because no one inside is presumed able to protect themselves.

  10. Robert says:

    As much as you may think it’s grandstanding, people seem to be forgetting that thingiverse is makerbot’s site, and if they feel uncomfortable having this content on their site, their have every right to remove it. I doubt they believe this will 100% stop this material being available, they just don’t want to be anything to do with it.

  11. Robert says:

    (Am I the only non-american posting in this thread by any chance?)

  12. Christian Restifo says:

    A quick search of Thingiverse this morning yielded several knives, slingshots, and swords. There was even a bomb release mechanism for an RC plane.

    Apparently, only *some* weapons or weapon-related items are being removed.

  13. MP says:

    To keep the designs available, Defense Dist. has put them up on

  14. alex says:

    “plastic filament was demonstrated to fire and cycle six times before breaking.” why would anyone want to do that, the plastic can be used for a mold which can easily be made into a metal part.

  15. Dave says:

    Oh well. F**k thingiverse. F**k makerbot. I wanted one of their machines but ill pass. I guess someone who won’t bring their personal politics into play with emerging technology will have to make a competing site and take away their business. The internet doesn’t usually look too kindly on censors.

  16. b00mslang says:

    The smarmy Canadian comment is not applicable. The entire Canadian psyche is different. In Canada, when a cop says; “Stop, in the name of the Law”, the peeps actually stop.
    Not so much so in America. Canada hasn’t tossed off its colonial roots and can’t decide if it’s a country or a provincial backwater outpost of Great Britain.
    The IRA didn’t need guns, they killed plenty of British soldiers with slingshots and pipe-bombs.
    Silly Canadian…

  17. Perry Chamberlain says:

    Censorship, Second Amendment, BLA BLA BLA……….
    I want no part of any group promoting guns.
    Take your paranoid, aggressive BS somewhere else.
    I joined this community to share and experience open thinking and creativity, not making things to kill people.
    Go hang out with other angry paranoid psycopaths, on the gun sites.

    You will not be missed.

    1. Sean Ragan says:

      Your commitment to open-mindedness is indeed evident to all.

    2. Libertarian Lurker says:

      “I want no part of any group promoting guns.”
      So I take it you have renounced your citizenship and refuse to pay taxes? LOL!

      The real hypocrisy here is that paranoia and aggression are the hallmarks of those who call for the govt. and its guns to aggress against individuals who have committed no crimes and merely wish to be left alone.

  18. Wayne says:

    No website is required to host data that the owners find offensive. That said, the data to create gun parts is just that – data. We now have governments in the position of saying, “This stream of ones and zeros is OK but this other stream of ones and zeros is illegal” It’s silly to think that such a law could be enforced in an age where digital information is getting easier to share.

    1. Sean Ragan says:

      Unless I missed something, the government is not directly involved in this decision. What’s happened here is that Thingiverse has exercised its rights under its terms of use. That’s all. They obviously have no interest in pissing off their user base, so the only thing that’s interesting to speculate about, as I see it, is what benefit they expect from taking a step which will obviously do so, to whatever extent.

      I have heard, in the context of the Wiki Weapon / Defense Distributed / Stratasys dust-up, about the possibility that a person who prints a plastic lower receiver may be potentially prosecutable under the Undetectable Firearms Act, and it seems at least possible to me that Thingiverse’s lawyers may be concerned that providing models that seem to be intended for producing plastic gun parts might someday be spun up into criminal charges under that act. At this point, no one seems to be saying that Thingiverse or its users have violated the law by posting or providing these data, and, frankly, my guess is this decision was made mostly for PR reasons–they don’t want Thingiverse and MakerBot smeared with the wrong kind of ink in the wake of the Newton massacre. I think it’s a totally rational decision, if not one that especially pleases me.

      1. Alan Chunkster says:

        Here’s something I’m not totally clear on-

        I read the text of the undetectable firearms act, and it appears to have a sunset provision, so unless congress subsequently passed something extending it, it doesn’t apply anymore? I’m not really sure.

        Also this is pretty ripe for a supreme court case at any rate, because while the lower is indeed a “major part” of a firearm, it is completely useless without metal parts to punch the primer. I’ll leave that one up to the lawyers to slug out…

        And lastly, iron filled filament would be the next logical step to produce a “detectable” gun, as long as enough strength could be retained to still function. Can’t be long…

  19. Nick Rishel says:

    Hello bittorrent.

  20. Brandon A Boyer says:

    This is a knee-jerk reaction to the events that occurred at Sandy Hill. I do not see this becoming an issue in the foreseeable future. Plans for zip guns have been available for a long time. Until technology advances to the point where we can make machinist grade parts from an inexpensive piece of equipment I see no point for this kind of censorship.

  21. icmc says:

    I don’t think it’s so much about the fact that it’s a printed receiver so much as it’s a step in the direction of a fully printable gun. OR it could also be the fact that yes this is a firing prototype “gun” (for lack of a better term) typically criminals want a cheap disposable gun (cheap .38/.22 throwaway type guns) in case of actually using them at a crime scene. Something that you could take the barrel off of and smash up with a hammer take all the other parts put on another receiver and you have another untraceable fire arm.

  22. Jack Van Gossen says:

    Screaming censorship is a bit over the top. Thingiverse, like Stratasys, found the manufacture of weapons objectionable, and removed files for said weapons. Pretty cut-and-dry, nobody’s rights were violated, mass crime will not ensue, we will still be just as safe in our homes as we were before – gun owners or not.

  23. Chris says:

    As the saying goes: it is not the weapon but actually it is the man behind the weapon who is responsible for all this chaos.

  24. MAKE | The Face of Printable Firearms: A Conversation with Cody Wilson says:

    […] content that “contributes to the creation of weapons,” in place since 2011, to remove a number of firearms-related models, including Guslick’s reinforced AR-15 lower receiver, from their […]

  25. The Face of Printable Firearms: A Conversation with Cody Wilson says:

    […] prohibiting content that “contributes to the creation of weapons,” in place since 2011, to remove a number of firearms-related models, including Guslick’s reinforced AR-15 lower receiver, from their […]

  26. Brad says:

    I’m not sure if it was mentioned but you can make your own UNMARKED GUN for you OWN PERSONAL USE by law. So thats why poeple buy what are called 80% Lower Receivers and simply follow instructions to drill it into a fully functioning AR15

    you can find 80% lower receivers at

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I am descended from 5,000 generations of tool-using primates. Also, I went to college and stuff. I am a long-time contributor to MAKE magazine and My work has also appeared in ReadyMade, c't – Magazin für Computertechnik, and The Wall Street Journal.

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