Introduction: The $6 Marshmallow Musket

Picture of The $6 Marshmallow Musket

Built like a small potato cannon, this mini-marshmallow-firing musket is not a thing of engineering beauty but its ultra-low cost and easy assembly make it good for mass production.

Step 1: Gather Tools and Materials

Picture of Gather Tools and Materials

tools (available at any hardware store):

PVC cement
PVC primer
a PVC pipe cutter, hacksaw, or some other way to cut through PVC pipe
a power drill
a 3/32" drill bit (just a tiny bit larger than the needle of a ball pump)
a file or knife to clean the ends of the PVC pipes

materials from the hardware store:

about 3' of 1/2" schedule 40 PVC
about 2' of 1" schedule 40 PVC
1 1" PVC ball valve
1 1" PVC cap
1 1" --> 1/2" threaded PVC reducer bushing
1 1/2" --> 1/2" threaded adapter

materials from the dollar store:

plumber's tape
1 ball pump
4 zip ties

Step 2: Cut the PVC Pipe to Length

Lengths don't have to be precise for this, so just eyeball it: I use about 2' of the 1" PVC for the pressure chamber and about 3' of 1/2" for the barrel.

Use your saw or PVC pipe cutter to cut to the appropriate length, then use a file or blade to clean up the area of the cut so it will fit in to the fittings.

Step 3: Dry Fitting

Fit all the parts together to make sure you understand the layout and that everything does in fact fit.

From front to back the order of the parts will be:

barrel of 1/2" pipe (will be glued to the...)
1/2" --> 1/2" threaded adapter (will screw into the...)
1" --> 1/2" threaded bushing (will be glued to the...)
ball valve (will be glued to the...)
compression chamber of 1" pipe (will be glued to the...)
end cap

Step 4: Glue!

Picture of Glue!

Now cement (almost) everything together. Do NOT cement the two threaded bits to each other.

To glue PVC, clean the area to be cemented then swab both parts with a dab of purple PVC primer. This sets almost instantly, allowing you to apply the cement. PVC cement is nasty stuff - use ventilation and don't get any on your skin. Like hair gel, a dab'll do ya. Once the cement is applied, fit the parts together tightly. Use a paper towel to wipe up any excess. Allow five minutes to dry.

Step 5: Drill

Picture of Drill

Air will be pumped into the compression chamber through the needle of the ball pump. Pick a point about half way down the end cap and use a 3/32" bit to drill a hole diagonally through cap. The location is to keep the outside part of the needle from bending when the musket is rested on end. The angle is to give the needle the maximum possible material to go through, for stability.

Plan your angle carefully, though - you don't want the needle bending when you rest the musket, but you also don't want the needle to miss the pipe.

Step 6: Prepare the Needle

Picture of Prepare the Needle

Because the hole is slightly larger than the needle (believe me, I tried making the hole slightly smaller and the needle just bent when inserted), you will need to wrap the needle in a bit of plumber's tape. 2-3" should do. Start at a relatively steep angle, maybe 45 degrees, but as you wrap it around gradually reduce the angle so that by the end you're wrapping it straight around. Think of it as building up a very slight cone around the needle, tapering toward the tip, so that it can find its own fit in the hole.

Step 7: Attach the Pump

Picture of Attach the Pump

Stick the needle in the hole. There will be some tape bunching up, but it should hold pressure (for a while - this is not a perfect design, merely a cheap and easy one).

Attach the pump itself to the compression chamber using the zip ties. You will probably need to attach two ties to each other to get all the way around. Once it is on tight, clip the excess and you're done.

Step 8: Operation

Picture of Operation

This musket is designed to fire mini-marshmallows, but should be able to fire bits of potato, apple, grubs, or anything else you can fit in the tube.

If you are using something that won't easily slide down the tube, the threaded connection between the barrel and the ball valve can be undone and ammo placed in the barrel from that end.

If muzzle loading, be sure the valve is in the close position when dropping in ammo.

Close the valve and compress the pump about five times. Aim and release the valve to fire.


Colonel88 (author)2009-11-13

Can anyone think of some effective ammunition for air guns? I want to make a custom one, but I also want to make it fire as many as possible different types of ammo. I'm thinking marshmallows or snowballs or something.

Andriffic (author)Colonel882011-06-19

I was thinking of:

Ice cubes
(cut off a section of pvc, plug it up, fill with water, freeze = perfect sized bullet)
Nerf darts,
lit smokebombs,
and possibly nails.
Actually nails would probably be a bad idea. But the list goes on!

freeza36 (author)Andriffic2012-10-16

I shoot pop its out of my blowgun (never tried my airgun) and they hurt terribly to get hit by. And I got a nail shot thru my hand. Ow.

tinyhooman (author)freeza362016-11-10


l8nite (author)Colonel882012-10-16

there are all kinds of ammo but you have to be careful even with "JUST" an air gun, A few years ago my then 45yo brother made an air rifle that shot steel marbles or ball bearings, he set up a bunch of boxes in the drive way as a target, the pellet went thru the boxes, the fiberglass garage door and put a HUGE dent in his wifes BRAND NEW car...

l8nite (author)Colonel882012-10-16

there are all kinds of ammo but you have to be careful even with "JUST" an air gun, A few years ago my then 45yo brother made an air rifle that shot steel marbles or ball bearings, he set up a bunch of boxes in the drive way as a target, the pellet went thru the boxes, the fiberglass garage door and put a HUGE dent in his wifes BRAND NEW car...

I wo0uld definitely recommend interchangeable barrels. maybe a 1/2" CPVC barrel for darts and small stuff, and a 1/2" PVC(its bigger) barrel for Nerf darts and paintballs, a 1" PVC barrel for potatoes and mega spitwads.

zappenfusen (author)2015-07-13


SMOKINACE99 (author)2013-06-21

Awesome design but note that in Canada the ball valve alone is 6$ along with the other materials I would evaluate this more at a 15-20$ design

somebody12345 (author)2012-03-10

if you cut off a peice of the barrel or pipe that size you could make foam sabos

polaris 250 (author)2011-10-12

Made this gun in 1'' shoots 250 yards

noahh (author)2007-06-19

I just got back from the hardware store and man it was madness. they didnt have a one inch valve but instead a 3/4 valve. So they paired it with 2 nipples and 2 something elses. Instead of 6$, just on pvc gear alone i spent... TWENTY FIVE DOLLARS!

beehard44 (author)noahh2010-10-28

hehe i spent only 1 dollar for a valve, endcap and a PVC nipple. It's a micro air cannon lol

Kryptonite (author)noahh2008-10-14

Ouch... Oh well u won't do that again... hopefully.

chickenliver123 (author)noahh2007-09-28

same here....

CrazyKommie (author)2008-01-20

I couldn't get the thing to work at all, tapering the needle was hard, but when i finally finished.. it just spat out barly any air and didnt even move the piece of paper that i made into a ball is there something im missing?

imkwl12345 (author)CrazyKommie2008-10-26

ummm you have to turn the ball valve as FAST as u can

beehard44 (author)imkwl123452010-10-28

and pump more air

beehard44 (author)2010-10-28

hehe, i had a lucky find! i just found a plastic bottle that fits nicely on your shoulder and it held 2L of soda before. All i need is some PVC pipe and some PVC hardware...

yardkarter (author)2009-10-25

I think the design is AWESOME for safely shooting marshmallows across a room. However, it is NOT $6. It was not so expensive just becase I used $5 extra of brass parts. Even though I used a cheaper valve, previously owned pvc primer and cement, AND owned the pump, it still cost around $20! 

sgt. frog (author)2009-07-28

hey i made this in 1 in. pipe to fire full sized marshmallows. it works great thanks!

amarsar (author)2009-06-21

I attached a bike tube valve with strong epoxy. it can hold 200 psi and nothing leaks :) and when i load it with a marble it shoots 600 feet :) its amazing. just use epoxy to keep the valve in place. oh, and my tubing is tested to 450 psi so it's safe.

slayermonk (author)2009-03-26

I made something quite similar, only difference being that, with the end cap of the 1" pvc, i drilled a 1/2" hole in it and inserted a schrader valve (tire valve) the valve cost me a dollar. i cemented it in place so it can hold 80+ psi (i havent dared go beyond that). I use an electric tire pump to charge it and i get quite some power out of it. the gun itself (not including pump) cost me around $5-$6 so it fits pretty much any budget.

amarsar (author)slayermonk2009-06-21

its easy to just cut a valve off an old bike tire. saves you a trip to the store :)

skimboarder33 (author)slayermonk2009-04-13


Check out my how to get a FREE Schrader valve instructable @

geek27 (author)skimboarder332009-04-23

Schrader valves can be found at a couple of stores. You may have found one by now, but they can be found at stores that sell auto parts. Schrader is also just the company name that makes the valves. The real name for the product is "tubeless tire valve." Hence the name, these things are found in bikes, car tires, and possibly more. There are multiple sizes, but I recommend a .453" tubeless tire valve. You can drill out either a 3/8" or 7/16" (7/16" is a better size, but 3/8" will work.) in the PVC endcap. the tire valve can then be inserted into the endcap. Since the valve is coated with rubber on the outside, simply pulling it through the drilled hole nice and tight will make it airtight. You may want to apply epoxy around it, but it's not necessary. The one drawback, however, is the fact that if you use a tubeless tire valve on this gun, it will be hooked up to a bike pump. The pump will be very difficult to attach to the musket due to the large sizes of bike pumps, so you will probably need to keep it separate from the musket. Below is a picture of the valve, and I hope that it works for you! (The picture is of a common tubeless tire valve, but they often come in various shapes, sizes, and often look a little different)

pyro4226 (author)2009-05-24

yea, add a video of the gun firing!!

robert the robot (author)2009-04-26

Can you post a video of this gun firing?

tony48 (author)2007-08-03

how much does a ball valve cost?

Metal4God (author)tony482007-09-24

bout 5-7 dollars

you know how the pump has to have a tube then the needle, my hand pump dosnt what do i do!

Not sure what to say - you can either find a needle or find another pump. Maybe you got a bicycle pump? If so, you can use a bicycle tube air valve instead of a needle - just make the hole bigger.

Ananand (author)graymalkn2009-04-14

Yeah, I have a bicycle tube air valve, but its connected to the bike tube. Do I cut it off, or can you buy the valve separately from the tube?

zach911 (author)chickenliver1232008-06-24

sire, i am afraid it will require a bit of plastic surgery and

i cannot get the needle to stay! i have tried the tape method, the hot glue method, and the epoxy method. none work! plz someone help...

If you have a tire pump then get a valve stem from the parts house. About$2 and can be mounted in the end cap!

when i went to a store called hibbets they had a 2 pk. of needles for $2 or a pump and a needle for $5

zach911 (author)Metal4God2008-06-23

it costs $1.50 at home depot in austin texas

Metal4God (author)zach9112008-06-24


Warlrosity (author)2009-04-12

In wanna make one woth a ajjustable valve and a trigger

sgt. frog (author)2009-03-24

I am a marshmallow gun arms dealer for the wee ones of the camp I work at. I have been trying to hit upon the formula for a marshmallow gun that can fire the large marshmallows effectively. in your plans, I have created the perfect design for this. I plan to shorten the barrel to maybe 1ft and muzzle load the mallows. (using a 1 in diameter pipe instead of a 1/2 in one.)

photis22 (author)2009-01-24

you sould use an explosive release valve, theres a realy good instructable on here somewhere if you search it

Kryptonite (author)2008-02-14

Dude that's pretty awesome!

What i did though was to hot glue around the outside of the pump's pin, then i stuck it in, it's been goin with some pretty solid use and the pin hasn't moved at all. Another good idea is to use an irrigation switch, which is loads quicker than a ball valve, so =move power ☺

Where u said that you could unscrew the barrel and insert something, i personally cut a small gap in the front of my barrel and slid a rubber pen grip over it to insert items, a personal favourite is grubs, found every where and make a satisfying *SPLAT* when it hits. if u think the pen grip wud let the air out, u'd be saprised, it doesn't.

☺ ♥♦♣♠ ☺

imkwl12345 (author)Kryptonite2008-10-26

i dont like 2 use grubs... i use ice >=D of course it is alot more dangerous. u get some pipe the same diameter as ur barrel and the fill it with water leaving 3cm at the top. freeze it and cut ur ice to ur desiered length and load. but be carefull these will pack a huge punch and can do some damage!

Kryptonite (author)imkwl123452008-10-29

I used to have a friend that had a spud gun, but shot oranges. Frozen oranges. He shot windows of houses and cars. It was ultimately cool, cuz the police found him, and sorta said "well, all evidence points to you, we know you did it, so... Well, If you keep going we'll have to pull you in."

So they new it was him and didn't really even give him an official warning! Meh, I like the sound of ice, but grubs are really readily available (at my place we got a bin of them.) and you can shoot anything! people, cars, houses, anything and no one will be tooo ticked off, just don't let them see you. *splat* yay!

SnakeFang217 (author)Kryptonite2008-03-13

Great idea i will hot glue around the pin

chickenliver123 (author)2007-09-18

is there anyway to make the air tank way shorter?

shorter how about BIGGER

nobody394 (author)Metal4God2008-10-08

yea u gatta hurt em with the marshmallow they need to pay in PAIN for the marshmallow

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