You can make a potato cannon using hair spray, an old barbecue grill ignitor, wire, piping, some glue, and of course a potato. You can buy a 3 inch diameter threaded pipe with a screw on cap, a section of 1 1/2 inch pipe, and a 3 inch to 1 1/2 in reducer fitting at any hardware store. Glue the reducer fitting into the end of the pipe opposite the cap and let dry, then glue the 1 1/2 inch pipe to the reducer. Place two 1 1/4 inch screws into the large pipe about 3 inches from the cap and directly opposite of each other. Next use 16 gauge wire and attach it to the grill igniter, and the other ends to the screws in the pipe so that when you click the igniter you get a spark between the screws. Place your potato into the barrel, and spray the hairspray into the chamber and tightly cap it shut. Click your igniter and fire your potato.