Instructions for building an autonomous sentry gun

Here are complete instructions (software, source code, build manual, hardware) for an autonomous sentry gun that will shoot anything that moves.

DIY autonomous sentry gun


    1. IT’S ALIENS!!!!!
      phew.*cries a little*
      Also, I beleive Ridley will be coming out with Alien 2 fairly soon.

  1. Cue the bullet-shaped case and childish voice saying “Who’s that?” and “I really don’t blame you.”

  2. Interesting, but highly illegal. And dangerous. My law school case books have several cases involving contraptions like these, and none of the cases ended well for the people who made them.

  3. I believe part of the Patriot Act allows the authorities (whoever that is) to enter your home when you aren’t home and they don;t even have to tell you afterward (I know landlords have to let them in for searches and are prohibited from letting you know they had been there). So, if an FBI agent enters my home whilst my robot is there with his finger on the trigger. . . .

  4. I see nothing that can go wrong with this…

    I would love to see this hooked up to a big super soaker..

  5. Shoot anything that moves.

    With what, a beam of infrared light?


    Show it firing off a few rounds from a .45 ACP at a piece of cardboard on a stick or something.

  6. “If you build one does it count as manslaughter or murder?”

    If you kill someone with it, yes, absolutely. Deadly force cannot be used to protect property, and people have been convicted for killing others with various types of booby traps, including trap guns. So far as I’m aware, this holds true in every jurisdiction in the United States.

  7. They’re called “spring guns,” and they’re rightly illegal in every state in the union. If somebody is killed by your spring-trap gun—it doesn’t matter who or what the circumstances are—you’re facing a murder charge. It doesn’t matter how many warning signs that you put up, nearly every state will lock you up for life. You’d have to be six kinds of stupid to deploy one of these.

  8. As I recall, some time ago somebody built a sentry watergun to reduce the number of people using his yard as a shortcut. I think I read about it here, actually…

  9. So, everyone’s saying about the laws and cases against people who made these sorts of things with firearms. What does case law say about less-than-lethal versions? Beanbag shotguns, mace/pepper spray, tasers, that sort of thing.

  10. @Scuba SM: What does case law say about less-than-lethal versions?

    I don’t know off the top of my head, but it’s still a very bad idea. There’s a principle in (U.S.) common law called the Eggshell Skull Rule: If your tort causes harm to someone, even if the harm is far greater than one would normally expect because of a physical condition existing in the person that you didn’t know about, you’re still just as liable.

    In other words, if you set up one of these traps with a (normally nonlethal) beanbag gun, and the person who gets shot happens to have an abnormally thin skull and dies as a result, then you’re on the hook just as though you’d set up a shotgun full of buckshot.

    So: Not recommended.

  11. “Reason reboots with no problems. That’s to be expected. It’s also to be expected that later, probably when he most needs Reason to work, it will crash again, the way it did for Fisheye.”

  12. Is it within normal policy for BoingBoing to post instructions on how to build illegal and highly dangerous weapons?

    Next maybe you can post a friendly guide to hijacking a plane. Hey, it’s only information!

  13. What if you set one of these up to shoot something akin to a small paintball only instead of with paint in it you’d put something foul-smelling like skunk spray?

  14. I was looking at your website ( and I was wondering if your open source software is compatible with Windows 7. I know how much you emphasize the fact that you’re not a programmer, however, my computer encounters errors when I run the installer. Is the software old, or am I doing something wrong?

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