You thought that the spud gun was cool. this shoots stuff at about 4 times the speed(and usually distance). i made mine to connect to an air compressor. but i have heard that you can purchase a normal automotive tire valve and do just what i did but drilling a hole into the piping.

Air compressor style cannon

You need this stuff to make the coolest gun ever but here are a few rules

1. you are dealing with pressures up to 120 psi. that means that if it explodes its like 120 pounds hitting you. i am not responsible for your idiot choices in using your cannon or in constructing it

2. never shoot anything at anyone with this. i have shot nails thru plywood from 20 feet away. this is not a toy and if you hurt someone they will kick your ass after they get out of the hospital.

3. this is just the way i made mine. i am not responsible for you making yours( sounds like rule #1 lol)

ok i found the galvanized piping is the best because 1 the connections are threaded so you cant really mess up. and 2 galvanized piping is rated to over 300 psi. so pretty much it wont break unless you screw up

you need this stuff to make a cannon

   1- 1 inch sprinkler valve

   1- 16 inch piece of 1 inch piping( normally they can cut and thread it for you. or buy whatever lengths you want... all these measurments are just what i think is comfortable

   1- 4 inch piece of 1 inch piping

   1- 12 inch piece of 1 inch piping

   2- 1 inch elbows

   1- 1 inch threaded ball valve

   1- air compressor male fitting

   1- 3/8 threaded to 1 inch( this is hard to find. so you might have to get a 3/8 to 3/4 and then a 3/4 to 1 inch.)

   lots of teflon tape

now here is the important part. check to make sure all the odds and ends work out. try them out at the store. who cares if grandpa is looking at you. you will notice that i didn't add on anything about a barrel. that is up to you. i have many different barrels that i use. and to make it cheaper many of them are sch 80 pvc. these are nice because they come threaded like the galvanized fittings. below are some examples of barrel diameters and uses.

wrap teflon tape around all the threads a few times. if you dont do it your cannon will leak air. then proceed to thread them together like the picture. if you cant see it then oh well lol.

the electrical system is a bit more complicated. i used to use 3 9 volt batteries wired together to a switch. but it is almost easier to use the manual open on the valve itself. it gives you some control over how much kick your shot has and it makes it really hard to misfire.

Barrels:

3/4 inch barrel- this is nice to shoot paintballs out of. and they hurt too. you can make a hopper that will turn your cannon into an automatic paintball gun... nice in paintball wars. lol

1/2 inch barrel- i use this to shoot the deadly stuff. i have found that 16 gauge nails with some electrical tape around the head so that it has a tight seal make nifty ammo but like i said these are dangerous. we only use them in shootouts

1inch and 1 1/2 inch barrels. these are the heart and soul of potato barrels. just twist the spud around the top till the barrel cuts the perfect size potato then stuff it down the barrel. these have been known to hit low flying airplanes lol