Introduction: Paintball Minigun HK-1

Picture of Paintball Minigun HK-1

I have been wanting to build a Paintball Minigun for a while and I decided now that I have the resources to make it happen, I should get this thing finished. Also please ask me if you have any questions, I would be more than happy to help.

Thank you, and happy building!

To build this Minigun a bunch of the parts that I needed were not available so I had to design them myself and 3D print them. This project took me about 2 months to build which I did not work on it every night. Most of the time was spent just figuring out how to design what I wanted.

The video above was the first time taking this bad boy out for a spin. This is not the top firing rate. I need to take some time and tune it in. In the video I show the barrels spinning by themselves, then the barrels spinning while dry firing, then firing the paintballs. Its hard to see the paint because I used green paint...Enjoy!

Step 1: Main Chamber

Picture of Main Chamber

The first thing I decided to do was to design a back ring that would attach the barrels to my bearing. I designed the "Rear Barrel Ring2" below and 3D printed it. I then tapped the 4 inner and 4 outer holes with a #4 tap. I then screwed the Rear Barrel Ring2 to a 4" lazy susan bearing using the 4 outer screws. Once that was done I marked, drilled and tapped 4 holes in a 25 tooth nylon sprocket. I got a 3-4" PVC Reducer coupling and marked the bearing with the inside diameter of the coupling and on the barrel ring of the bearing I cut the metal corners off so the would not rub as the bearing spins. On the Sprocket side I folded the corners up so the whole thing slides into the 4" side of the coupling. Then I secured the bearing to the side of the Coupling with 4 screws. Finally I cut 2 slot in one side of the coupling so the chain could travel through. I also had to drill the center of the main sprocket out to about an inch so the barrel could fit through later.

Step 2: Motor Housing

Picture of Motor Housing

I bought the cheapest cordless drill I could find at Menards so that I could use the motor and the battery to power the barrels. I opened up the drill and you need keep the battery hook up and the motor with the torque setting chuck. You need this chuck because you can set it to 8 or 9 and if you ever get something stuck in the spinning barrels it will activate the chuck and not break your barrels.

To mount the motor I designed a ring that will fit on the motor and screw to the motor with 3 screws already holding the motor together. Then I purchased a 2" compression fitting, slid the motor inside and secured it with 3 screws through the 3D printed Motor Mount Ring. I then cut a slit half way around the PVC tube so the chain could go through. I also drilled a small hole toward the end so the wires could go through.

I took the cap to the compression fitting and cut the top off to make it as short as I could. Then I 3D printed a plug to fit inside the cap to close it off. I glued this cap into place. Now the cap is still removable so that the chain can be accessed later.

I also made a cap to be glued on the back of the compression fitting and this cap has holes in it so the motor can breath and not overheat.

Step 3: Mounting Motor to Main Chamber

Picture of Mounting Motor to Main Chamber

To mount the motor housing to the main chamber housing I had to 3D print a dual ring to hold these together. Once printed I hooked up a nylon chain between the motor and the main sprocket. I made sure this was aligned and slid the mounting bracket over the 2 housings and secured them both with the 3 screws in each of the housings through the mounting ring. Then I developed a chain guard so nothing gets caught in the chain. I used 2 screws in each of these to hold them on.

Step 4: Regulator and Handle Mounts

Picture of Regulator and Handle Mounts

I added a 3" tube of PVC to the main chamber and also on the side to house the regulator. To mount the regulator housing to the main chamber I had to create another dual ring mount that was slightly different than the first one for the motor and I used 2 of these.

Next was to mount the 2 points to where the handle will attach later. I used 2 pieces of 1-1/2" couplings and designed a base to connect them to the main chamber. I first screwed the couplings to the 3D printed base then screwed the base to the main chamber. Then I put a Plug cap inside each of the couplings and screwed them into place. These allow the square parts to be easily mounted to later with the handle.

Step 5: Internals

Picture of Internals

Now for the goodies...

I used a Smart Parts Ion Paintball Gun for this project. I used the main chamber of the gun, electronics, regulator, and ASA.

I purchased a remote quick connect and replaced this straight connector with the 90 degree elbow that was on the regulator. Then I bought a 1/8" micro line fitting to replace the fitting that was in the ASA. I put all of this together in the 4th image above.

To mount the regulator I used the mounting holes from the ASA and I had to develop and 3D print a mount so it would mount to the rounded interior of the regulator housing. I mounted the regulator so the adjustment nut is sticking out past the housing.This is so we can adjust it later.

Step 6: Internals 2

Picture of Internals 2

On the guns circuit board I had to locate the power, program, and trigger buttons and solder a wire on both sides of these switches. Make sure you label these so they will be easy to find later. I also had to get some 1/8" and 5/32" tubing so that I could extend the hoses to reach the new locations for the regulator and such. To attach the gun to the inside of the main chamber I had to design more rings to tighten to the gun using bolts to squeeze the gun then the rings have 3 holes to mount to the inside of the main chamber housing. Once the rings are installed, the electronics need to be crammed in between them and zip-tied. Now the feed neck needs to come off so the gun can be slid into the main chamber.

Be sure to drill a hole in the side of the regulator housing and the main chamber for the air lines to fit through to the regulator .

Step 7: Handle

Picture of Handle

To make the handle I first started with taking apart an old Sidewinder flight controller. After digging down deep into the controller I only needed a few components. I only used the grips, the buttons, the circuit board, and the post that the grip holds onto. Then I chose which buttons on the controller that I wanted to do used. I needed 4 buttons: one for power, programming, motor spin, and firing. I found which buttons were which by using a multimeter and checking continuity of the wiring until I found the buttons that I wanted (2nd and 3rd photo).

Then I soldered wires to the circuit board on the paintball gun. I soldered a wire on each side of each of the switches for power, programming, and firing.

I built the handle out of 1/2 inch square metal tubing and some 1/2 inch rod. I welded all of these pieces using a mig welder. Please see photo notes as to where each of the following parts are located.

The following lengths were cut from this 1/2 in square tubing:

2 pcs. 5" long

1 pc. 3.25" long

2 pcs. 11.5" long

4 pcs. 2" long with 1/4" hole drilled in them

1 pc. 4.25" long

1 pc. 8.25" long

1 pc. 1.75" long with 1/2" hole drilled in it

The following was cut from 1/2 in rod:

1 pc. 7" long

2 pcs. 2.25" long

1 pc. 5.25" long for under the handle later

Once the handle was made I uses a 3" to 2" fitting and put it on the back of the main chamber. Then I 3D printed a disk that has a recessed hole in the center for the 1/2" tube to fit (see "Shaft Support file"). I glued this disk inside the fitting. The front of the handle is secured but drilling a 1/4" hole through all 4 front tubes and the square caps on the front of the handle supports. Then use some 1/4" quick release pins so you can easily disassemble later. The back is supported by drilling a 1/2" hole through the 1.75" short tube under the handle. Then slide the 5.25" round tube through that and into the hole in the back of the main chamber. Fasten the round tube to the square ube by drilling a small hole and using a small bolt and nut to keep in place.

Step 8: Battery Holder

Picture of Battery Holder

The drill motor needs its own battery that is seperate from the guns 9v battery. I used the battery that came with the drill which was 18v. I also used the connector at the bottom of the drill as means to attach the battery to the gun. I took the drill body with no internals and cut off the bottom of the grip. Then I drilled 4 holes, one in each corner to mount it to the underneath of the gun. I drilled a hole in the regulator tube so the wiring could go through and be hidden.

Step 9: Wiring

Picture of Wiring

The wiring is pretty much straight forward. I drilled a hole out of the back of the 3" X 2" reducer at the back of the main chamber. This is where all the wiring will run out from the gun and to the trigger grip.

Run the power wires from the gun circuit board and wire them to the power wires coming from the grip, and do the same for the program wires, and the firing wires. For the last set of wires hook the ground wires from the battery connector directly to one of the wires coming from the drill motor, take the other wire from the circuit board and run it to one of the wires on the grip that you want to use and take the other wire from the grip and run it to the other wire on the drill motor. You should be able to put your drill battery in now and hit the rotate button on your grip and it will spin. PLEASE be aware that there are no safety switches here and take out the battery when you don't intend on shooting it.

Leave enough slack in the wiring that you can take the handle off the top and place it to the side without stressing the wires. Also I used wire loom and wrapped the wires going from the back of the housing to the grip, from the motor housing to the main chamber, and from the regulator housing to the main chamber.

Step 10: Barrels

Picture of Barrels

For the barrels I used 6 pieces of 1/2" ID and 5/8" OD PVC pipe that are 22" long. These are for the main 6 barrels. Then I used 5/8" ID blue PEX piping, which I used 6 of these at 10" long. These slip over the back of the barrels. Last I use a 1.25" ID PVC pipe that is 22" long that will run on the inside of the barrels for support and to hide the paintball gun barrel.

I 3D printed 4 more disks just like the one I mounted to the bearing but these 4 are through holes and so the barrels will slide through them. I put the first ring about 10.25" from the ends of the barrels. Then I slid the blue pex tubes over the barrels until they pushed up against the ring I just put on. This will allow about 0.25" to stick out of the pex at the back of the barrels. This will allow the tubes to sit down inside the disk that is attached to the bearing later. I took the next 3 rings and put the 1st one about 1/2" from the front of the barrels, the next at 1.75" from the first and the last one at 1.75" from the last one. Then I slid the 1.25" tube through the center of all of the disks and made it flush with the front of the front disk. This should allow for 0.25" to seat into the ring on the bearing.

I used a lot of a glue called Plastic Repair that I picked up from Farm and Fleet. This stuff is great and really sticks the PVC to the 3D printed ABS material. I tried 5 minute epoxy but it just breaks off and your barrels will fall off. I used this Plastic Repair around the barrels and rings as I could get access to. Once that dried then I took the barrel assembly and seated it into the ring on the bearing and glued it as much as possible. Be careful not to glue the bearing in place.

Step 11: Final

Picture of Final

Once everything dries it is time to paint it. I used a plastic primer and a textured flat black that I picked up at Lowe's. Make sure you plug up all of the holes so the motor and paintball gun do not get painted.

Overall I am very happy with this build. The barrels wobble a little when they get spinning but that is due to the play in the bearing and I could get a tighter bearing if I wanted to fix it. The gun has not been adjusted, only to switch into full auto mode. I have not tried to get a faster rate of fire yet but I will be doing that soon to see how fast I can get it to shoot. Also later on I plan on putting and elbow where the hopper is now and run a tube to a backpack and have the paint force fed in since my tank will be on my back anyways.

I hope you like my Paintball Minigun HK-1. If you do PLEASE vote for me above in the right hand corner to show your support and I will keep the projects coming. Thank you for looking and please let me know if you have any questions.

Happy shooting....


Icedstone (author)2017-04-15

I need a few parts like the sprockets and chain. Where did you purchase those and how may teeth is the smaller sprocket? Can you send me the files for the barrel centering bracket?

Kidfast Fast (author)2016-08-19

me and my friends are doing a 5 day campout war. Day and Night. No Food but u r allowed to bring water anyway are base needs to be heavily fortified and armed.

kurtz64 (author)Kidfast Fast2016-09-08

This would definitly get the job done

Rubythedoo (author)2016-09-07

Did you purchase 3d printer? If so, how much was the cost, and what kind? If not, where did you get the 3d printer, and where were you able to print it? Did you ask a friend? Did you go to a school? Or office place?

kurtz64 (author)Rubythedoo2016-09-08

For that project I did have a 3D printer. It was a XYZ Davinci 1.0. I got that printer because it was one of the cheapest out there with that bed size. I had to do a lot of tuning and mods to get it just right but not a bad little printer. Check your local Craigslist.

Kidfast Fast (author)2016-08-19

Can u send me a copy of the 3d model so i can print it at home thanks if u can.

Email me at

McBulletsponge. (author)2016-08-17

What program do you use to edit these files my printer doesnt recognize them

kurtz64 (author)McBulletsponge.2016-08-17

Sorry about that. Those are Autodesk Inventor files.

Wolfram90 (author)2016-06-23

Is there any way you would be willing to sell the 3d printed parts needed as a kit by chance? If so, how much would that run?

kurtz64 (author)Wolfram902016-06-24

I might be willing to sell just the 3D printed parts. Please PM me if interested.

Wolfram90 (author)kurtz642016-06-24

I'm new here (actually just made an account so i could comment) so how do I PM you? ^^'

Wolfram90 (author)Wolfram902016-06-24

Got it. :)

kurtz64 (author)2015-07-21

Thank you everyone for the comments and for voting for me. Not sure what I will do with it now but it was very fun to make.

DaraganthD (author)kurtz642016-05-10

hey if your willing to sell it id buy it in a flash XD

kurtz64 (author)DaraganthD2016-05-10

Possibly might sell it.

DakotaK7 (author)2016-04-05

I think this is awesome. Can you explain in a less complex way how to make the mini gun? Because I can't understand some of the steps on how to make it. I really want to make this paintball gun. Other than the complex steps, I think that the mini gun would be fun to build.

kurtz64 (author)DakotaK72016-04-06

I would be glad to help you. What steps do you need help with?

DakotaK7 (author)2016-04-05

I think this is super awesome. Can you explain how in a less complex way on how to make it? Because I really want to make that mini gun but I can't understand some of the steps. Other than the complex steps I think that the mini gun would be awesome to make.

Adrian_West (author)2015-11-09

This is fantastic. I has read this and I don't understand something. How did you synchronize the barrel location with the marker firing. I could see how miss timing could be a mess. If I just can't read please pointe to the page. ;)

Big Baneser (author)Adrian_West2015-12-15

It actually isn't synched at all which is kinda cool because it keeps the minigun effect without a super complicated mechanism.

The actual marker is centred between the rotating barrels meaning it doesn't have to wait for stuff to move because the moving parts are always outside the cone of fire. The before last picture in step 6 shows this better than my words. The author could probably explain this better than me too.

Hope I helped!

kurtnotkirk (author)2015-09-22

This is one of the coolest things I have ever seen! Awesome!

jaydogg_321 (author)2015-08-07

how much does it ruffly cost to make?

Mystery9829 (author)2015-08-05

Hey, I love the idea, but wouldn't it be a tad better if there was a strap or something holding the paintball canister down?

The Black Python (author)2015-07-20

that is so AWESOME vote & fav from me

Naktibalda (author)2015-07-19

Looks EPIC!

damavox. (author)2015-06-29

If you don't have a 3d printer, you can make the same out of wood. Also you can take the wood and use to make a silcone mold and then make the parts out resin.

GunGeek369 (author)2015-06-28

THIS THING IS AWESOME, Definitely voted on the pvc contest. As far as the instructable goes the video would have been a lot better had you did some video of the paint balls hitting a piece of plywood or something. It would add to the greatness of this a lot. Do you plan on attempting to get it to fire out of all 6 barrels?

GunGeek369 (author)GunGeek3692015-06-28

Oh, as a suggestion using a micro controllers a human sensor and some servos you could make it into an unmanned century gun to defend your base.

RemyLeon (author)2015-06-21

Wow! This is really insane! It looks awesome! what is the rate of fire of the final stage? You got my vote for sure!

kurtz64 (author)RemyLeon2015-06-23

Thank you! The rate of fire is not that much now, I cannot be certain as I don't have a chrono. But those the rate could get a lot better and when I get time I will improve on it.

Temo Vryce (author)kurtz642015-06-26

Based purely on what I'm hearing in the video. I would guess that you're currently at 8bps. Although I have been wrong before.

Nice project, but the barrel wobble losses it for me.

MechEngineerMike (author)2015-06-25

Great work, this thing looks like it could have been a movie prop in Machete!

JaredE2 (author)2015-06-23

Way awesome man!

JaredE2 (author)2015-06-23

Way awesome man!

Downunder35m (author)2015-06-22

I really don't like it when people 3D print realistically looking guns, but for this one I do make an exeception!
What I don't like:
Hmmm, not much, just would love to see a longer video in action with some nice detail shots.
Things I like:
The Instructable really looks good!
The workmanship and idea behind the mods is just so good that I think it will be used a lot in the paintball community.

What could be improoved:
I know everyone hates those comments but anyway:
Since it is already shown on a car, why not use a little air compressor and reservoir for car use?
The pics and details are very good, but I think folks would appreciate a video showing the assembly of the gun, does not need to be in real time, just so it is possible to see all steps and stop the video on the go to get it just right ;)

I don't say it it much but wish you the best to win somethng great as I really like this one :)

kurtz64 (author)Downunder35m2015-06-23

Thank you for taking the time to read and make comments. I like the constructive criticism. There is no doubt this could be improved, that is why I named it with a -1 behind it with the intent of future versions. Thank you for your support!

mquiring1 (author)2015-06-22

Awesome work!

kurtz64 (author)mquiring12015-06-23

Thank you!

Zumbahl1 (author)2015-06-22

This thing looks awesome. Nice work!

kurtz64 (author)Zumbahl12015-06-23

Thank you for taking the time to look!

43totheN (author)2015-06-22

Please pardon my confusion: does this have 1 actual barrel or 6? Or to ask a different way, does it have Gatling-type firing mechanics?

Well executed build regardless!

kurtz64 (author)43totheN2015-06-23

This fires out of a single barrel. Butl you would not notice the difference if not shown.

tomatoskins (author)2015-06-22

Now that's badass!

kurtz64 (author)tomatoskins2015-06-23

Thanks you!!!

TheLoneWanderer (author)2015-06-22

Pretty neat, though the need for 3d printing kinda makes it less available for all to make

kurtz64 (author)TheLoneWanderer2015-06-23

Believe me, if I could have made it all without a printer I would have. But the internals needed to be printed unless they were machined. So that is the other option, but I shared the files so people can use them as they want.

EverythingDiy (author)2015-06-22

So awsome

kurtz64 (author)EverythingDiy2015-06-23


CandyLove11 (author)2015-06-22

How cool!!! I love paintball!!! I play it a lot with my brother!! Thanks for sharing !!! :D

kurtz64 (author)CandyLove112015-06-23

Thank you for looking!

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