There have been a lot of "guns" posted lately that utilize rubberbands. I deciede to share my AA cannon. Sorry that there is no pics of it being built (I built it quite a few weeks ago and took no pics) but you should be able to build it with my directions. It will put a AA battery out of sight.
Also, it is really cheap; it only cost me about $13
It really is a very simple, small scale pneumatic cannon. Overall length is about 18 inches, height is 4 inches. The barrel and air chamber are both removeable, which makes it easy to modify.
Step 1: Get Parts
Okay, here's the part list and where I got them.
These materials I got at Lowes Hardware:
One 12-inch long 1/2-inch nipple (pictures 3 and 4)
One 1/2-inch ball valve with threaded ends (picture 6)
Two 1/2-inch close nipples
Two 1/2 inch elbows that are threaded (screw on) on one end and need to be glued on the other
One 2-inch to 1/2-inch threaded reducer
One 2-inch coupler
One 2-inch cap
These I got at Ace Hardwate:
One PVC Purple Primer (trust me, you need this if you don't want it to leak)
One PVC Cement
One roll Teflon (Plumbers) Tape
2 inches of 1/2 inch PVC pipe
8 inches of 2 inch PVC pipe
MAKE SURE YOUR PIPE IS PRESSURE RATED!
These I got at Schucks Auto Supply:
One pack (icludes two) tire replacement valves for a .453 rim hole (picture 2)
Step 2: Get Taping and Then Screw!
Wrap teflon tape around all the treaded ends, and start screwing. You don't need tape on the barrel, so wrap the first close nipple in t-tape and connect the ball valve to one of the elbows. You should not be able to see the nipple once it's screwed together, like in the picture below.
Do the same thing to get other bend connected to the 2-inch to 1/2-inch bushing. Again, you should not be able to see the nipple once they're screwed together.
Step 3: Get the Valve On!
The best place to put the tire valve is on the cap; the cap is thicker than the pipe and puts the valve in a convenient place. Drill through the cap with a 9/16 drill bit. Use superglue to seal it.
Step 4: Prime and Cement
Use a 2 inch long section of 1/2-ich pipe to connect the 2 bends; coat with primer and then cement. Squeeze them together tightly and hold for a few seconds. Remember to be liberal with your cement, not your ballots!
Primer and cement the coupler to the bushing, then the pipe to the bushing and the cap (which has the valve on it) onto the pipe.
Yes, I used the photo twice ;)
Step 5: Ammo Preperation
While you wait a few hours for the cement to dry, prepare your ammo. A small amount of duct tape makes AA battery's fit perfectly. Also fun to shoot is marshmallows and those small, packaged carrots. Finally, a tube full of water gives of a cool bang like a firecracker.
Step 6: Pump It UP
Use a pump that has a gauge and can pump at least 120 PSI. Everything here is rated to at least 180psi (the 1.2 pipe I used is 600psi) so 120 should be fine.
Check for leaks.
Step 7: FIRE!
Take it to a secluded place, or just walk out your backdoor and aim for a piece of plywood.
Until you have fired it and seen what it can do, please don't fire it within 200 yards of anything of value.
Aim, and flip the ball valve open as fast as you can.
Those movies are two shots I did. Sorry for the crappy video quality.
Step 8: Different Cannon, Same Ammo
This cannon does the same thing, and costs about the same. It is easier to aim, but take up much more space.
It is made entirely from 1/2 inch pipe.
If enough people can't figure out how to build it, I'll do another unstructable
Step 9: Conclusion
I hope you have fun with this, and here's a couple concluding comments:
Remember to use LOTS of primer and cement. A little overflow is a good thing.
NEVER shoot anyone with a AA battery (some animals are acceptable, such as opossums). Marshmallows are okay.
I know you can use a modified sprinkler valve, but I wanted a cheap, compact, fun little cannon.
I Love friendly comments. Please, no comments about this being dangerous or me being crazy, I already know these things.