How to build a combustion cannon

The combustion cannon is the simplest spud cannon to build, and operates on the principle of igniting hairspray to create pressure in the guns chamber to expel the projectile.
To operate, put in your projectile (muzzle loaded, then unscrew the back of the cannon and spray in some hairspray (amount will vary). Quickly close the back of the launcher and then press the igniter when ready. If you would like more power for your cannon, build a propane meter for the spud launcher. This video will show you how to make this awesome combustion cannon.