This is a WARNING. Do NOT under ANY CIRCUMSTANCES point this at anybody or any living creature. It's a very strong little pen shooter, and can leave more than a mark. I am not going to held accountable for your actions, so if you are not mature enough to handle this carefully... turn away NOW.
Now for the good stuff :)
This is a fun and easy (and cheap) little toy that I invented the other day. It's very strong and shoots very far.
What you'll need:
1 Office Depot Ballpoint pen - very cheap -- 1 dozen for $0.89
(this might work with other pens, but I haven't tried)
1 Rubber band of medium length
Step 1: Making the Barrel
Pull the writing end and the little plug on the back of the pen off.
This is a very easy step, if you can't figure it out, you LOSE. Please try again.