3D Printed Exploding Projectiles – For A Potato Cannon

At the end of last summer I showed off a potato cannon that my father built 15+ years ago and went through some of the firing procedures. While launching spuds is both fun and satisfying, I’d be lying if I didn’t dream up ways to make tracers, flechettes and exploding shells. Sadly, acting on those dreams would likely put me in the purview of the Destructive Device sections of the National Firearms Act. So, until I’m licensed to manufacture exploding root vegetables, I’ll have to live through the scientists/experts on YouTube.

The King of Random channel has a solid variety of entertaining and educational short videos p, some of which delve into the firearms world to explain how certain things work.

In one of their latest episodes they show off a previously made cannon built from PVC piping. However, rather than heading down to the Piggly Wiggly for a sack of potatoes, the guys use a 3-D printer to make some aerodynamic projectiles.

Not only that, but they leave their newly created grenades hollow, allowing for the addition of gunpowder. After filling each one with black powder, The King of Random team uses a pistol primer and a nail to “arm” the mini explosives.

Sadly, we have to wait for the next installment in the series to see the results. I am looking forward to it – not for my own ideas, mind you, but in the name of science and experimentation, we all need to see if they were successful.

Here’s a few screenshots, but scroll down for the imbedded video.

3D Printed Exploding Projectiles For A Potato Cannon


The King Of Random YouTube Channel


LE – Science – OSINT.
On a mission to make all of my guns as quiet as possible.
Twitter: @gunboxready
Instagram: @tfb_pete


  • TheNotoriousIUD

    Im glad I was a kid waaay before 9/11 or else I would have ended up in Gitmo.

    My friends garage was basically a bomb factory. Our specialty was a horizontally fired, shoulder launched, explosive filled Estes model rocket.


    • RSG

      “Statue”? ???

    • Fortunately, children under the age of 10 aren’t considered legally culpable under Texas law, otherwise my idiot friends and I would have committed sooooo many felonies with our field expedient bazooka fights. A short length of PVC pipe and an appropriately sized bottle rocket = 100% FUN (until someone loses an eye).

      • TheNotoriousIUD

        Ah, growing up in Texas.
        Ive still got a burn scar from roman candle on my back.

    • Dan

      My parents thought i was interested in NASA and space when I told them i would like to build model rockets. Yeah not so much.

      • TheNotoriousIUD

        Mine too.
        I was interested in sending things into orbit though…..

    • jcitizen

      Same here except we kids didn’t know there was a statue! ๐Ÿ˜€

  • Kovacs Jeno

    OK, please explain me, why it isn’t a destructive device?

    • USMC03Vet

      Obviously because of the gun show loophole.

      • Kovacs Jeno

        so, it is because it is for the children?:-)

    • raz-0

      Dunno exactly, but I would suspect that an answer might be down the path of why fireworks aren’t destructive devices.

      In this case if someone involved has their explosives license appropriate for fireworksy things, and they “are designed primarily to produce visible or audible effects by combustion”, then they are fireworks and all legal as display fireworks. They exceed the content for a commercial firework.

    • Alex Agius

      Less than 1/4 oz of explosives in the projectile I imagine

      • Porty1119

        I mean, you can fiddle with explosive shotgun slugs and it’s not a DD if the charge is below 1/4oz. Ignition is spotty; you’ll have better luck by just epoxying a primer to the nose. The bang is nice when it hits a hard surface.

  • USMC03Vet

    We have to ban these assault launchers with the thing that goes up.

    – some politician soon

  • Without some sort of set back arming their projectiles are extremely dangerous. Just the inertia of the nail on launching could set it off and detonate the round in the tube making a great grenade for the shooter and those around it. Designing a safe reliable fusing system for projectiles is one of the major hurdles for amateurs. The point detonating rounds have a very low chance of going off if they do not stabilize and hit directly nose on. The design with the nail will tend to bend the nail or break the plastic nail guide if it hits wrong and does not detonate. There needs to be some serious thought about unexploded ordnance cleanup for those that doe not go off.

    To keep this off the DD registration requirements for each projectile, the pay load including priming compound needs to be less than 1/4 oz total payload of explosive composition.

    • TheNotoriousIUD

      The nail is a good option but I agree that its likely to snap off due to length. It should be more like a thumb tack with a wider head and should only stick out maybe a quarter inch.
      I doubt theres much chance of launch inertia causing premature detonation but that could be fixed with a bit of krazy glue connecting the nail shaft to the nose cone or run the nail through a semi rigid spring. For safer arming the nail or tack should be attached to the nose cone before the two body halves are connected.
      A safer option would be a weighted nail on primer system set in the tail piece that uses impact as the force to drive the nail into the primer.

      • A better option is a spring loaded cross fin on the firing pin that is retain in position by the launch tube so when it clears the tube it pops out and arms the round. Relying on a dab of glue or some friction of plastic is dumb and unsafe.

        • TheNotoriousIUD

          Theres a low probability of inertia forcing the firing pin onto the primer. Glue would work fine.
          Launching homemade explosives is always unsafe.

          • jcitizen

            When I was a kid I used plastic soda straw to keep the nail head glued in place, to fight recoil forces – worked like a champ. The plastic straw was just frangible enough to crush on impact. I was still smart enough to launch using remote controls, No way was I gonna be any were near that mortar! Never had a premature detonation. Did have one scary misfire, and land right in front of the launcher, but a pile of railroad ties blocked any possible shrapnel. Stupid kid stuff, but at least not so stupid that we ended up experiencing Darwin’s law.

            I’m glad I got that stuff out of my system at a young age – and the Army helped flush any further interest after that.

    • iksnilol

      Are… are you a soccer mom? “Waah, it could blow up”? For real?

      • Just an engineer that has seen way too many bad things go wrong. I suggest you look up what happens when teh bird bombs in 37mm launcher goes off in the barrel. They also used about the same amount of powder and there is now people without fingers or working hands.

      • Bill

        Homemade explosive devises are hand surgeons’ and trauma docs’ wet dream. A local kid has a seeing eye dog due to fun and games with a bottle bomb. I understand that he can still differentiate between light and dark.

        • iksnilol

          Pfft, like that’s gonna happen to us.

          Now hold my beer.

          • Bill

            You’d make a great hillbilly. That’s high praise around these parts.

        • Alex Yamach

          You’re right.

          I still have bits of steel in the tips of my left hand from an exploding CO2 cartridge that I was packing full of match heads way back when I was a dumbazz teenager.

          Thank God that the jaws of my dad’s vise were perpendicular to me, so that the metal of the exploding cartridge blew out to the left & right of me, instead of catching me in the face and neck.

          Lesson learned.

    • Tassiebush

      I was thinking about inertia too.

    • Exoskeleton

      Whenever I scroll through the comment sections and see your name, I always stop to read what you wrote. You always share interesting and valuable information, thanks for that. I agree with you on your statement.

  • Blake

    that’s an awful lot of work put into something made to go “bang”

    the cool thing about building spud guns is that PVC is available in pretty much any diameter you want, so you can size the bore to fit the projectile of your choice e.g. ping-pong ball, tennis ball, etc.

    kudos for the pistol primer idea; much safer to launch than e.g. a tennis ball full of match heads &ltgrin&gt

    • Gary Kirk

      Being a welder has some perks.. I use steel pipe, acetylene, and golf balls.. Pretty interesting ๐Ÿ˜‰

      There is a video of some guys on the YouTube doing it, will see if I can find it..

  • Edeco

    Be interesting to see with a metal case, make sure the powder gets stoked up completely before blowing apart. Only if done by a trained professional in compliance with applicable laws of course.

  • Scott Connors

    Come on! Never go full potato… ๐Ÿ˜‰

  • roguetechie

    The USMC has been doing related, though I’d bet much more sophisticated testing on 3d printed ballistically launched explosive ordnance…

    But the USMC isn’t using a reprap prusa and home depot… So this is way cooler.

  • Phil Ossiferz Stone

    How do they get away with this without registering each projectile with the ATF…?

    • jeff

      less than 1/4 oz of explosive compound per projectile

      • Cymond

        How much explosive is in 40mm chalk marking rounds? Because ATF confiscated those as DDs.

        • jeff

          the proellant and primer is what makes it explosive. As you not, this applies to all firearms ammunition, but the law specifically states there is an exemption for SMALL ARMS munitions. Their letter/ruling seems to state that since these rounds are not for small arms (ie, they have a bore over 0.5 in diameter and are not a shotgun) the normal ammunition exemption does not apply to them. Interestingly, this same logic would also mean that all aerial flares would be considered “low explosives”. Which is odd, considering the US Coast Guard REQUIRES boaters to have these as mandatory safety equipment. So if you are a boater, you can either be in violation of a BATFE ruling, or in violation of a USCG ruling, you have to pick one.

      • jon spencer

        How about a sealed baggie filled with a Oxy / Acetylene mix instead of of powder?
        Baggies with this mix can make a loud bang.
        Dangerous too.

        • jeff

          not an issue, because the gasses are not considered an explosive

  • Mike

    Potato guns are felonies in tx

    • Yyyup, third degree felony. They’re classified as illegal zip guns under Texas Penal Code Title 10 ยง46.01.(16) and ยง46.05.(a)(5) unless they’re registered with ATF or somehow being used in an official law enforcement capacity.

      • Rick O’Shay

        Well, that’s really good to know. I had no idea, and had been considering building one.

      • Alex Yamach

        Wow. In Texas, yet!

        I spent a week in North Carolina visiting a cousin many years ago…. His uncle ran a car repair shop, and a friend of his ran a gas station close by.

        When things were a bit slow, for giggles, they’d pull out their potato mortars & lob a spud or two at each other. I saw one of those friendly duels – had no idea how far those suckers could shoot a potato!

      • jcitizen

        They’re legal in my state, but as kids we still threw them away after each session playing with them. To us they were a throw away disposable toy. Sometimes we’d make rotten egg launchers just for Halloween, and build them out of expended fireworks lawn shell card board tubes with a flint striker and hair spray for fuel. Chuck the whole thing in the nearest dumpster once the eggs were used up.

        • For small stuff we used PVC pipes as a kind of gunbarrel atlatl– with a little practice an M80 will fly a million miles if you light it at the bottom of a 2-3ft pipe and whip it overhand with a wrist snap– but for larger payloads (like soda cans or balloons full of gravel or ziploc bags full of shredded poison ivy and half-frozen water) we used one of those water balloon slingshots that were popular in the ’80s. We had complex ballistic tables worked out for various size/weight/shape payloads, so that with the band attachments at a certain height and the sticks at a certain width and the cup pulled back a certain distance at a certain angle, we could reliably achieve a two or three foot CEP inside of a hundred yards.

          • jcitizen

            A tip of the hat to you – I would loved to have gone that far! (thumbs up!)

  • Tritro29

    ISIS has been doing the same exact thing for a couple of months now with aerodynamic “boots” for rifle grenades and then deploying those via drones.

    Not sure this is going to be funny for long.

    • jcitizen

      That must be why I’m seeing special drone killing units in Iraq, and the weapons they use to shoot them down or electronically zap them from a distance. I could see that coming a mile away, when I saw my first affordable drone.

  • Karl Vanhooten

    Wow! Blast from the past. Back in the mid-1950s, we had a throw toy just like the projectile, except it was smaller and hand-thrown (cap bomb). The tiny “bang” was powdered by a rolled cap. For you youngsters, we had also cap guns with 50 imprinted powder dots for shooting in our Hopalong Cassidy and Gene Autrey Winchesters.

    We could also make real gunpowder from our Gilbert chemistry sets. Today’s little boys can maybe make cookies from an Easy-Bake oven.

    Of course for real excitement, we rolled M80 fireworks in glue and BBs for a pretty realistic “hand grenade.” Why no one lost an eye or hand was just dumb luck.

    • Rick O’Shay

      My dad bought me a similar hand thrown cap bomb back in the early/mid 80s. The nose was basically a little nipple that could take one of those plastic “primers” from a cap gun ring. I’ve considered 3D printing something similar, with a hollow nose that could take some lead fishing weights or something, for my own boy. He’d get a kick out of having something like that.

      • Cymond

        FWIW, cap bombs are still available online, such as Amazon and eBay.

    • CountryBoy

      I remember those…… they were a LOT of Fun……. ahhhhh the smell of cap smoke in the morning…..

    • Alex Yamach

      “We could also make real gunpowder from our Gilbert chemistry sets. Today’s little boys can maybe make cookies from an Easy-Bake oven”.

      ROTFL! Sadly, you’re dead on about the Easy-Bake oven…

      BTW, I was watching an episode of “American Pickers” a week ago, and they came across one of the original Gilbert chemistry sets. The owner said that these sets could not be legally made today because of all of the restricted chemicals that the original sets had.

      I used the M80/cherry bomb technique you’d mentioned as a kid, except in a different way. My fellow miscreant and I would glue a old nut or small stone to each firework, then we’d row out into a tidewater river where we knew there would be fish.

      One of us would start rowing our old boat like hell, while the other would sit in the back with a cigarette, light one cherry bomb at a time, and just drop it off the stern.

      The resulting explosions looked like a Navy destroyer laying down a depth charge pattern on an enemy sub – definitely cool. And occasionally, a stunned fish (perch or carp) would float up to the surface, and we’d scoop them up for bait or lunch.

      Illegal as hell? Yup. Fun? Check.

      • jcitizen

        I had one of those Gilbert Chemistry sets, but refused to use the original items. I got every thing I needed from under the kitchen sink and the farm, and veterinary supplies. There is no stinking way they could outlaw everything that can go boom!

    • disqus_PDmXLtTxJj

      I’m only 32 and I had a small armory of cap guns, nurf guns, and BB guns. I wouldn’t want to be a kid now n’ days though I hear they have to wear NURF. LOL NO ONE DO ANYTHING AT ALL…… YOU MIGHT GET HURT! Cool true story found an opened box of original lawn darts in my barn after my wife and I bought our house, still haven’t opened them yet( although I kind of want to). ๐Ÿ™‚

  • Capn Jack

    If you don’t have all of that fancy equipment and want some real distance and accuracy, build a pneumatic cannon. Look them up on the WEB.

  • Mikial

    It’s putting crap like this on the internet that gets the Feds and ATF all fired up to tighten controls over things. If you want to build this kind of stuff, that’s fine, but don’t tell the world about it or you will end up like the kid that rigged a Glock up to fire from his drone and then put it on You Tube . . . in big trouble. And beyond that, why tell terrorists and criminals how to build this? That’s about as bright as when the NY Times ran a two page spread diagram showing exactly how the Boston Marathon terrorists built their bomb. Show a little responsibility, people.