you will need a Bic pen , a pair of needle nose pliers . a long stick or rod , scissors , friction tape , a water balloon and a pair of wire cutters.
Step 2: Gut and cut Bic pen
First you gut out the pen then cut the pen in half. by pulling the pen part out with a pair of needle nose pliers then pop out the top cover with a stick or metal rod. then you cut it in half with the wire cutters.
Step 3: Attach the balloon
Now you pull the balloon over the pen and then secure it with tape like so.
Step 4: Fire
To fire you load a projectile (BB's , Seeds , etc) then pull the ballon back and release