What’s cooler than marshmallow cannon? Not too much in my book! Thanks to the inspiration of a 8th grader named Joey, we were able to take his design and recreate it for you right here on the How-To Community!
Joey was working on his marshmallow cannon project to bring to the Makers Faire, so he constructed a plan and headed to his local Home Depot in the Phoenix area to enlist the help of one of our store associates. Jerry, a millworks associate, was more than happy to help, and went above and beyond to turn Joey’s design into reality. Joey’s marshmallow cannon made it all the way to the White House, where President Obama was please to try it out for himself!
SAFTY FIRST….
- Always assume that it is loaded and ready to fire.
- Never point it at anyone or anything that could get hurt or damaged by it.
- Always be sure of your target and what is behind it.
Materials needed:
4 – 2” 90deg elbows S x S 1 – 1” 45 deg elbow S x S
1 – 2” Tee S x S x S 2 – 1” male adaptors
1 – 2” x 1” reducer S X S 2 – 1 ¼” caps
2” PVC pipe cut to: 2 @ 22”, 1 @ 10.5”, 2 @ 4”
1 ¼” PVC pipe cut to: 6”
1” PVC pipe cut to: 2 @ 4”, 1 @ 24”
1 – 1” in-line sprinkler valve PVC glue
1 – ¼” close nipple 1 – ¼” coupling
1 – momentary switch 1 – toggle switch
1 – shallow junction box 1 – blank box cover
Wire connectors 2’ – 18GA. Wire
1 – air pressure gauge 1 – tire valve
Here are the steps that I took to build my marshmallow cannon:
Step 1: Cut PVC piping to the lengths listed above.
Step 2: Dry fit all the pipes together as shown so that you can ensure proper fit.
Step 3: Drill a hole in the tee where you will place the tire valve. Install the valve into the drilled hole ensuring that the rubber gasket is on the inside of the pipe.
Step 4: Using a ½” drill bit, drill a hole into the side of the 2” PVC pipes and thread in the 1/4” close nipple. Be careful not to over tighten, as this will strip the PVC. You may want to use pipe joint sealant or silicon adhesive for a more air tight fit.
Step 5: Thread the ¼” galvanized coupler onto the threaded nipple and then thread your pressure gauge into the coupler. Use pipe joint sealant on all of these connections.
Step 6: Now that you have everything test assembled, it’s time to take it apart and glue all the PVC joints together. Apply PVC cement to the inside of the couplers and the outside of the pipe and use a twisting motion to get a good seal. Do Not cement the barrel in place.
Step 7: Now it’s time to add the sprinkler valve. Apply joint compound to the male adapters and then thread the valve into place.
Step 8: Now we can begin wiring! For power, we will be using two 9 volt batteries, wired in series. Follow the below wiring diagram. Put all the junctions into your small junction box. The safety switch and trigger switch can be housed inside of a small PVC tube as shown.
Step 9: Use zip ties to attach the junction box to the sprinkler valve. You can also use zip ties to attach your trigger switch to the cannon as shown or leave it unattached for remote firing.
At this point you are ready to test your marshmallow cannon! We advise starting at a low pressure, around 10 psi. Make sure to check for leaks and repair as necessary. Make sure that your sprinkler valve is functioning properly before you increase pressure. You may want to increase gradually. Once you are sure that there are no leaks, you are ready to take your first shot!
We hope that you get lots of enjoyment out of this awesome project, and you can check out Joey's website at lwjm.us
this is great! thanks much.
I built two of these to be used by my scout pack in a for fun competition. We will do a relay race ( timed relay: which team can load, prime and fire the most marshmalows in 5 minutes) and farthest shot competition. Should be a blast!
I have a couple of comments/questions below:
comments:
1. the marshmallow is placed in the tail end of the barrel. (sorry if this is a repeat, didn't see it in the post)
2. the marshmallow is too large so you will need to roll it between your hands to make it longer and thinner.
3. Rolling the marshmallow will make the marshamllow sticky, or in my case, you may already have sticky marshmallows because you left them in the garage while you were working on the cannon. 
roll the marshmallow in flour. The mallows will shoot twice as far.
Question:
1: What is the recommended max PSI? I've seen on other sites that it is 30 PSI. However the PVC is rated at a maximum of 280 PSI. Not suggesting going anywhere near that high. maybe 40 or 50 PSI. Just want to know what the technical limit is and whether 50 PSI will really cause my cannon to explode.
thanks,
Kelly
