me and my buddies came up with this design... (only a true Iowan can build a good spudgun, we know how to use our newly harvested fields well
gun design:
3" pvc; 4 feet
5" pvc; 1.5 feet
one of those 3" to 5" cone connector things
glue and tape to seal it all off real nicelike, and file off the tip of the gun, so when you put a spud in there it cuts off excess making a nice fit
fueling system
This part is where we became engineers for a day
we used one of those cup holders you can buy seperate to put on say a bike or something, to hold on to our can of hairspray. this was attached to a long rectangular plate, which was part of the sliding mechanism we came up with. i can really only describe it in a picture...
http://s93558501.onlinehome.us/pictures/spud.jpg
see, you slide the hairspray, held in the cupholder, to the left, and the 2 holes meet up, opening up the inner cavity of the chamber
anyway, load the potatoe, about 2 inches in, spray the hairspray, THEN pamp the potatoe allmost into the fuel chamber, this compresses the hairspray, AND adds the oxygen stored in the barrel of the beast, pop the trigger and bang. right into the shootin' car.