This is not a real gun, and ping-pong balls will not generally damage humans unless shot at very close range, at the eyes, or swallowed.However, a number of aspects of this project are dangerous.It uses electricity, and we do not modify the electrics of the leaf blower. However, you should observe the safety instructions that came with your leaf blower.Do not put your hands or fingers into the leaf blower when it is on or even just plugged in.Do not place your eye or anyone else's into the gun's line of fire.