Intro : how to make a pen gun
This instructable will show you how to make a speargun out of a regular clicking pen...very powerful,effective,and fun!
The best uses for this pen gun would be to make loud noises in class by shooting it at a filing cabinet, as well as shooting the insides of the pen into the textured ceilings that are very common in schools and offices. WARNING:DO NOT FIRE THIS AT PEOPLE, IT IS VERY POWERFUL!

Youtube Video