This is a simple blowgun that will shoot a pen cap over 20 feet! It is made from relatively simple materials and could cost nothing if you already have the parts!
Warning! This is an extremely dangerous blowgun! Do not aim it at people or animals, as it could cause serious damage! I am not responsible if you or a friend get hurt using this device! This instructible is designed for your entertainment. If you build this, please please please take all safety requirements possible to ensure the maximum safety of you and anyone around you!
Step 1: Materials
A piece of 1/2 inch PVC pipe(The longer it is, the farther away the pen cap will go)
A pen cap big enough to fit inside the pipe
A cone of memory foam(I happened to have this one laying around)