Mini Cannon I built this mini cannon with under $3. I paid $1 for the combustion chamber, the pen was something from around the house and $1 for the electric lighter, which got covered in hair spray after a few test shots so we switched to a grill igniter from our Portable Cannon. From: JohnnyMcKinney Views: 63 0 ratings Time: 00:06 More in Science & Technology…