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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.
 
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Step 1: Gather tools and materials

Picture of Gather tools and materials
marshmallow musket 015.jpg
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!
marshmallow musket 019.jpg
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
marshmallow musket 011.jpg
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.
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zappenfusen16 days ago

grubs?

SMOKINACE992 years ago
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
Colonel885 years ago
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.
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...
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 was thinking of:

Ice cubes
(cut off a section of pvc, plug it up, fill with water, freeze = perfect sized bullet)
Pop-its
(http://chemistry.about.com/od/4thofjulychemistry/f/howpopitswork.htm)
Paintballs,
marshmallows,
Nerf darts,
lit smokebombs,
confetti,
and possibly nails.
Actually nails would probably be a bad idea. But the list goes on!
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.
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.
if you cut off a peice of the barrel or pipe that size you could make foam sabos
polaris 2503 years ago
Made this gun in 1'' shoots 250 yards
noahh8 years ago
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 noahh4 years ago
hehe i spent only 1 dollar for a valve, endcap and a PVC nipple. It's a micro air cannon lol
Ouch... Oh well u won't do that again... hopefully.
same here....
CrazyKommie7 years ago
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?
ummm you have to turn the ball valve as FAST as u can
and pump more air
beehard444 years ago
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...
yardkarter5 years ago

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. frog6 years ago
hey i made this in 1 in. pipe to fire full sized marshmallows. it works great thanks!
amarsar6 years ago
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.
slayermonk6 years ago
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.
its easy to just cut a valve off an old bike tire. saves you a trip to the store :)
WHERE DID YOU BUY THE SCHRADER VALVE!!! thanks!!
Check out my how to get a FREE Schrader valve instructable @
http://www.instructables.com/id/How-to-Get-a-FREE-Schrader-Valve/
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)
tirevalve.jpg
pyro42266 years ago
yea, add a video of the gun firing!!
Can you post a video of this gun firing?
tony488 years ago
how much does a ball valve cost?
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!
graymalkn (author)  chickenliver1237 years ago
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.
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?
sire, i am afraid it will require a bit of plastic surgery and liposuction.....lol...jkjk
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
it costs $1.50 at home depot in austin texas
weird
Warlrosity6 years ago
In wanna make one woth a ajjustable valve and a trigger
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