This article on how to make a really powerful "shooter" out of a pen.
1. Drag out the refill with ink and the top of the pen.
2. Cut off the pointed part of the pen (it will be easier to shoot).
3. Cut an office rubber band in half so that there would be two elastic strips. Mark the center of one of the resulted rubber bands with a point.
4. Draw a rather thick point (one can do it by a highlighter).
5. Take both ends of the rubber band and pull them down from both sides of the pen. Fasten them with an adhesive tape, allowing ends to get out of it. Not to hurt anyone, the ends of the rubber band must be hidden under the adhesive tape.
6. To shoot, put the refill through the bottom of the pen on the side, which is used to write.
7. Having pulled the refill to the top of the pen, place a rubber band on it so that it would find itself between its two sides and the refill end would lean against the marked point.
8. Tighten the rubber band with the refill in the middle, keeping the "gun" in another hand.
9. Take aim and fire.