Printing a gun is hard

Caleb sez, "The Department of Defense ordered that 3d printed gun removed from the Internet. That didn't work out. You can still download it and print it. I did, and found that the files are a mess and not really functional. I also took a cool timelapse video of the printing."

1. the scale on the individual files was way off.

I suspect this has something to do with the printer it was designed for. It seemed very close to being 1 inch = 1 mm. Not a completely uncommon problem. Manually resizing got some files to look right, but I found many simply wouldn’t resize.

2. Almost every single item had errors.

If you’ve done 3d printing, you’ve found that a model can have all kinds of issues that will stop it from printing correctly. I found every single item for the gun had errors. I actually learned a lot about how to repair non-manifold items from this exercise, so it was good in the end.

Some items, like the hammer and the hammer springs simply would not print. I ran them through systems to repair them and fix errors. It would say that everything was fixed, but when I tried to “slice” them for printing, the software would crash. This means that my gun is incomplete. It has no hammer. Not really that big of a deal to me.

Timelapse of the 3d printed gun being printed. (Thanks, Caleb)


  1. You know, zip guns are so much easier to make.
    And right up the ally of Boingboing’s resident steam punks.

    1. I know a guy who actually built a functional steampunk-style rifle. Of course he’s a professional armorer.

    2. Arguably, pneumatic guns are much more steampunk. At least one of the very early models had bellows and(while I don’t think that anybody actually did so) they would certainly be much easier to integrate into a steam-pressure driven system than would today’s admirably refined; but somewhat depressingly functional, cartridge based designs…

      1. pneumatic guns that shoot clockwork Leyden jars with sundry brass filigree would be worth an extra 17 steampunk Jeter units

        1. Would the Leyden jars be more or less steampunk than my gutta-percha-cased white phosphorus/luminiferous aether based incendiaries? 

          I find those to be just the ticket when I’m out imperialising in my zepplin and the locals take cover in thick brush!

      2. There was a period of time where air rifles out performed the regular rifles of the day.  Trouble was they were really expensive.

        Lewis and Clark had an air rifle for shooting big game on their expedition.

  2. It says a lot about the DoD’s competency (at least at the policy-making echelons, I don’t doubt they have competent technical staff) that they believe you can remove something from the internet.

    1. I’m pretty sure that any takedown request would have been under the auspices of the US Department of State Directorate of Defense Trade Controls.

      I would also suspect, albeit without hard evidence, that the guy who got handed this takedown assignment rolled his eyes so hard they practically fell out. Even if he does think that you can just order ‘The Internet’ to remove a file, his job probably also involves a certain amount of realism about what US weapon exports are hot commodities among nation states looking to steal new tech, what US weapon exports are desirable but-not-being-reverse-engineered-by-the-Chinese, and what exports may be illicit but are basically a joke. 

      I wouldn’t be surprised if Distributed Defense objects to paperwork on philosophical grounds(and the takedown probably did them more good than harm, PR wise); and so it is entirely possible that the ‘liberator’ manages to be noncompliant in some way(if nothing else, the four people with internet access in North Korea could have downloaded copies!); but any DDTC employee who wasn’t a bit annoyed at having to chase down a weapon inferior to hardware that was being phased out before the Civil War would have had to be barely sentient…

      1. I would also suspect, albeit without hard evidence, that the guy who got handed this takedown assignment rolled his eyes so hard they practically fell out

        Well, don’t feel too bad for him: as a State Department functionary, I’m sure he’s used to implementing futile policies by now

  3. Have you considered that the authorities have tweaked the files into unusability?

    The way to remove something from the internet is not to have the offending data erased — it’s to flood the internet with so many false versions of the information that the original can never be found.

    1. This could lead to some pretty fun trolling. Put plans out there for a Liberator II, but when constructed and fired, just makes a sad trombone sound and falls apart.

      1. “I think the 3D Printer’s infected with an anti-Happy-Mutant Trojan.”
        “I tried printing a Liberator but when I pulled the trigger it only popped out a flag from the barrel with “Just look at it.” in Comic Sans.”

      2. That does bring up an interesting point though. What happens if someone knowingly puts plans for a gun online that they know isn’t safe, e.g. could or is intended to break in a way that will harm the firer.

        1.  If you feel the need to 3D print a working gun rather than buying one legally that was made to proper standards, then you get what you deserve however it works out. It’s a firearm, not a toy, and 3D printing these is just stupid. I don’t care what your conspiracy theory about govt tyranny is either, by the way.

          1. If you feel the need to steal bread rather than buying it legally, bread made to proper standards and licensed by the government, then you get what you deserve …

            The phrase “you get what you deserve” is a giant red flag that perhaps you may not understand the full range of reasons why X persons do Y things or the Z outcomes they may or may not deserve.

          2. While I agree with the gist of your argument, comparing bread to weapons made primarily to entertain and/or kill people leaves you just as guilty of violating all sense of rationality.

    2. That tactic has been used by the Copy Cops in the private sector to slow torrent distribution of movies and games early in the release cycle(on the logic that long-term victory is impossible; but the most valuable sales are early, so a modest delay can be worth it); but it would be trivial to defeat in this case:

      In the case of a leaked film copy or the like, only the release group has ‘authoritative’ information on what the file is supposed to look like, so a would-be downloader doesn’t have good ways to distinguish between the real thing and a fake.

      Here, though, DefCad is still up, and still distributing other files, just not these ones. All they would have to do is publish the SHA1 sum(s) of the archive, or each file, and it becomes trivial for anybody who obtains a copy through other channels to verify its authenticity. And, since the SHA1 sum is not, by itself, useful for much of anything(it’s just 160bits of meaningless garbage, useful only because the same input will always produce the same SHA1 output, and it is very difficult to craft an input that produces a desired SHA1 output), so it is unlikely to be export-controlled.

      Unless further evidence comes to light, I’d be inclined to suspect that the fact that hackaday has a much cheaper 3d printer than Defense Distributed, and probably different software, probably didn’t help. ‘Print-Ready’ 3d model formats aren’t nearly as mature as print-ready 2d document specifications, and even those can have ugly edge cases.

  4. Commenters on the post say that if you print the files on the same printer that DD uses, they print without any issues. The author acknowledges. So, mystery solved. The files are not full of bugs. You just have to print them on the intended device.

    1. Well, that’s like a .pdf that prints only on HP printers. It’s supposed to be a universal file format; if it’s not, then there is something wrong with either the file or the interpreter. We’re still early in this game with .stl files, so it’s hard to say if it’s the file or the software.

      1. I agree, in principle, but if I search the foggy annals of my memory, I vaguely recall a time when only Apple printers would print certain postscript files, even though PS was supposed to be a universal format. Standards, especially new standards, are hardly universally implemented.

      2.  Agree with joshuabardwell.  In the real world guaranteeing a “universal format” works universally involves extensive testing on multiple hardware and software combinations and endless tweaks to line up the results.  Java is obviously intended to be cross platform but that doesn’t guarantee that any particular Java program is going to run exactly the same on two different platforms.

      3. The 3d printing community uses software for this is still very rough. The free program used by most people is Skeinforge. It is a bit of a mess. The author doesn’t want other people working on the code, because he says that it will break if changed the slightest bit. Given its behavior and documentation level, I believe him.

      4. Only the news organizations & talking heads said you could “download and click print”. There are not a lot of standards for this kind of work; scale is important, and this is still the “wild west” days where there’s still some level of “pull yourself up by your own bootstraps”, the implications of which are that you might need to slightly modify the files to fit scale or limitations of your printer/media. 

  5. This is sort of par for the course for anything “open source” (quotes not because of any derision towards open source software, but because I feel slightly dirty using the term for things that lack actual source code). If you want to build whatever open source product on a platform it doesn’t support (or in this case, print it on an unsupported printer) be prepared to have a lot of the same sort of difficulties getting everything to work as intended. This isn’t a fault of the gun as a project so much as it is a symptom of releasing a work in progress to the world.

    1. Well put.

      But then, my thought is, if people start saying “open source development is exactly what will fix problems with the 3D printed gun!”, authorities will next start trying to find some deluded way to crack down on open source development.

  6. Even though he was upfront about not being serious about it, Caleb sure seemed pretty dismissive- “oh, I had to scale some stuff and and a little futzing didn’t immediately fix everything, so it must not work”.  Sort of like “I tried cooking a recipe I had in German run through Google translate, and it didn’t really taste great, so I don’t think soup’s a big deal”.

    Pointing out that a zip gun would be easier to make and more robust seems about as short-sighted as a government official saying “nah, we don’t have to worry about that, nobody’s done it yet” (a few weeks ago) or “oh noes!  we’ll make them take if off the interweb!” (a few days ago).

  7. A great deal of the “danger” controversy seems to revolve around the plastic elements of the 3D gun being undetectable by screening. 

    If that’s true, I always wondered what a builder would use for brass casings, bullet tips, springs and firing pins.

    1. For the bullet: wood perhaps. For the casing: maybe we go back to musket-style where there is no casing. I believe the springs are already in plastic. The firing pin is currently a nail; not sure if you could switch this with anything. A nail might not be enough to show up on a wand detector though. Or it could be hidden along other metal items in such a way that it would nor arouse suspicion.

      Ultimately; I look at this as an assassin’s weapon. It’s novelty isn’t that you can print it yourself; people have been able to build their own firearms for a long, long time. Building something in plastic without a lot of tooling is where this is special. It’s not made for distance shooting; there is no rifling and the barrel is very short. I haven’t looked at it that closely, but I believe it’s single shot since the mechanism is so simple, so it’s not meant to carry a clip for defense. I wouldn’t want to use this to hold off an intruder. Asking them to wait while I reload wouldn’t fly. This is an assassin’s weapon. Full stop.

      1. I’d argue it’s just a prototype for proof-of-concept.  

        However in practical terms… your description sounds unnervingly correct.  Considering this will eventually be cheap, probably untraceable (I can think of efforts to ‘stamp’ the material for 3D printers to be chemically unique, but that would require massive international regulatory control) and undetectable by anything but highly sophistication scanning technology,   Even then I can’t imagine it couldn’t be designed to disassemble in a way that each piece in unrecognizable.  All you’d need is one bullet…

  8. I find Caleb’s comments very weird.  I downloaded the files from Mega and, aside from the fact that they were scaled in inches instead of millimeters, found no errors whatsoever in them.  After having rescaled them, reorienting one or two and grouping the smaller parts so that the printing went faster, I had no trouble with the print whatsoever.  

    The only problem I found with the “gun” was that the plastic bar that connected the hammer to the coil springs that drove it was too weak.  It snapped after the first trigger pull.  I replaced it with a piece of M3 threaded rod and the trigger action was operational.  

    I did not print this “gun” to fire.  To save filament, I printed the barrel with a light infill.  The whole assembly reminded me of nothing so much as an ancient Very flare pistol.

    One note, the “threaded” barrel had no threading of any kind.  I assumed that Cody was talking about rifling.

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