This is a cool pen gun that can be made in under a minute with a Pilot G-2 seven or 10 mm pen. It shoots about ten to fifteen feet. All you require is the Pilot G-2 pen. Make sure that you use that this specific pen only, because no other pen functions like so and can be made into a gun.

Step 1: Step 1

Unscrew the top of the pen and remove the ink cartridge.

Step 2: Step 2

Push the pen's retracting/extending pieces on the end out with the cartridge.
Then, whack the other end of the pen lightly but rapidly against a surface hard to pop out the spring. You can now discard the end of the pen, you no longer need it.

Step 3: Step 3

Drop the top of the extender/retractor into the other end of the pen's shell.
Drop in the spring.
Drop in the other half of the extender.

Step 4: Step 5

Push the parts in tightly wit the cartridge, which you now no longer need. Congratz! You have finished with your pen gun and can now shoot at classmates/co-workers by pushing the extender piece down.