Any suggestions for a cannon (preferably cheap) that can put a tennis ball, or a tater over a football field or more?

ok that helps a little (thank you) but how do you install it or build it into the gun? plans?

I've only built a couple cannons in the time that this hobby has interested me (in other words, I'm new at this) but is there a better way to fire a pneumatic cannon than a diaphragm? As of now it has become a real pain in the a**, having to keep replacing it everytime it tears or breaks.

thanks for the help guys

hey im looking for a good material to make a diaphragm (for my pneumatic gun) out of, preferably cheap but at this point, whatever works the best.... thanks