To make a potato cannon you need about 2 feet of 3 inch pvc, 2 feet of 2 inch pvc, a reducer, a cap, an igniter and some hair spray. Glue the reducer between the two pieces of pvc and cap the 3 inch pipe. Drill a hole about half way up the 3 inch pipe and insert the igniter. Put a potato in the 2 inch pipe and push it down to the reducer. Open the cap on the 3 inch pipe and spray in some hairspray, you don’t need a lot. Close the cap and push the igniter.