This gun makes a loud pop when fired and will surprise anyone nearby.
Depending on the air pressure this gun can be a safe prank or a powerful air gun that is dangerous. A safe pressure to play a prank would be anywhere from 10-20 psi, but as a gun this should be fired at NO greater then 45 psi . At 70 psi or greater you are in danger of having the bottle explode and that would not be very pleasant.
This is a really fun project and the videos don't due it justice.
You really have to try it out to understand, and besides it is free and easy!
Step 1: The Hole
Step 2: Fill it with liquid
Step 3: Fill 'er up
Step 4: Executing the prank / Firing the Gun
Warning! This gun fires its cap at high velocities and can hurt someone or break something if you are not careful. This prank is best performed outside. At 30 psi this thing put a big dent in a soda can knocking it across the yard, but a fort five psi what ever you are shooting at could be destroyed (including glass).
Have fun and be careful.
Thanks for reading.