Where can i find plans at?? Anyone make one? how far do they usually fly?

The best way is to make a combustion or pneumatic cannon with a 2.5" PVC barrel.


2.5" PVC is kind of hard to find, but its out there. Try SpudTech.


Then just add a chamber, and an ignition source if combustion, and a valve if pneumatic.

IBTATF warning!

Check with the ATF before embarking on making one.  IIRC the ATF had rulings on tennisball guns because the fuzz on the balls would catch fire, thus rendering them Destructive Devices.  If you were to use compressed air and not a flammable substance to propell the ball, then there would be no problem.  It would not be a firearm, then.

Stay safe in whatever you do with it.

Dave.

ETA.  Damn someone beat me by mere seconds.