Before I build my first (pneumatic) cannon.

[starman]

Excuse my dad by the way, he's new to internet forums

Hey it's all cool. I'm a dad so I know the routine. He's probably more excited about it than you are..

I'm glad he's working on it with you.

[ammosmoke]

Usually you can just drill off to the side of the guide rod and leave the solenoid.

[ImHUGEnJAPAN]

I built my first pneumatic cannon about two months ago. This site is GREAT! I couldn't find those green Orbit Master sprinkler valves so I used a RAINBIRD CP-100 and it works great! 15$ for the valve and 5$ for the blowgun. You can mod it the exact same way as the Orbit Master and it's rated at 150 psi. The mod is very simple it takes five minutes. (I would weld the air chamber side for added safety, but that's just me) I solvent welded my threads, but apparently you don't have to. I would really like to be able to use different barrels. Next time around I will do some things differently.

If you go with an over under design make sure to put the valve behind the barrel to eliminate dead space.

You can easily find everything you need in the 2" sch 40 section at the hardware store. I just told the guy at Lowes what I was making and he was all excited to help find all the parts I needed.