It doesn't look like an airsoft gun but it shoots like one.
Step 1: Materials
All you need is a bottle with a screw on cap, a balloon, and a knife.
Cut the top off the bottle and cut out the center of the cap with the knife.
Cut off the bottom of the balloon and put it around this piece.
Screw on the cap over the balloon.
Step 5: Shoot
Load bbs, pebbles, or anything that can fit inside the gun. Simply pull back on the balloon and shoot. I compared this to one of my airsoft guns that shoots 350 fps and this shoots the same. Im not responsible for anything you do with this gun.