DIY Compressed Air Launcher for Projectiles

Build a gas-powered marshmallow shooter

Launch Time: The Physics of Catapult Projectile Motion

Pneumatic Cannon

Pneumatic Line Thrower - T-ISS

Stomp Rocket Launchers - Science World

How to make an Air Powered Water Balloon Cannon (Launcher)

Homemade air gun

Tutorial: Home Made Air Gun Silencers, Airguns Wiki

Hang 'Em High Antenna Launcher - Nashua Area Radio Society