I love this project. It involves fire, projectiles, electricity, and is easy to put together from commonly available parts. This mini cannon fires airsoft pellets, is fueled by alcohol, and is made almost entirely from parts found in a standard BBQ lighter. The total cost is under $5.
About half of the BBQ lighters out there have a divide in the gas reservoir which makes them not work for this project. In case you have trouble finding a suitable lighter, the exact one I use in this video is a 'grill zone flexible lighter'.
Outside of the lighter the only parts that are required are two self tapping screws, one 1/4" diameter bolt, hot glue, and the barrel. The barrel can be taken from a broken airsoft gun, or you could simply use the tube from a plastic or metal pen as long as it fits the pellets.
A cotton swab soaked in 90% isopropyl alcohol is rubbed around the inside of the chamber, the rear bolt is replaced, a pellet is loaded and the cannon is ready to fire.
Be sure to check out my latest article that shows how to make simple and effective darts for this mini cannon: https://nighthawkinlight.wonderhowto.com/how-to/make-ninja-darts-for-lighter-mini-cannon-0132338/
You can also come check out my YouTube channel for many more projects, and subscribe to be updated when I post new ones: https://www.youtube.com/user/Nighthawkinlight