This instructable will show you how to make a cheap and easy "slingshot" small enough to fit in your pocket but strong enough to break stuff! A word of caution before we get started, depending on how well you make this thing you could seriously hurt yourself or others, the household pets, or various nick nacks. Now that you are properly warned, let's go!
Step 1: Gather the needed materials:
one regular sized round ballon
one empty juice bottle
optional: corn starch or baby powder
Step 2: Cut off the top of the juice bottle
Just as pictured, you want to cut it so that you are left with a bell shaped piece. You can throw away the bottom piece, we're done with it.
Step 3: Trim the edge
Turn the top upside down and look carefully at the inside edge. If any of it is curled or turned inward, trim it off until you have a nice wide opened without any curled edges.
Step 4: Cut the balloon.
Almost done. Cut the neck of the balloon off right where the picture shows. Next cut off the lip on the other end of the neck and set that aside. You should be left with what amounts to a round rubber pouch and a makeshift rubber band.
Step 5: Attach the balloon to the juice bottle top
Stretch the balloon over the neck of the bottle top. Make sure you get on as straight as possible. Did you notice the grooves on the bottle neck? Take your make shift rubber band and slip it over the balloon and into the deepest groove on the bottle neck. This will hold the balloon on nice and tight. If you took the time to grab some baby powder or corn starch, drop just a pinch of it into the balloon and shake it around a bit. This will keep the balloon from sticking to itself in the near future. The finished product should look something like the picture below.