A pen gun i made a while ago, I have spent about six months perfecting it since then. Also, one of the awesome things about this pen gun is that it can be FULLY ASSEMBLED with the needle in it. This is very fun for target shooting and can be made in about 5-10 minuets. ( I am not responsible for any accidents and/or bad choices that occur while using this. THIS IS A WEAPON, USE IT WITH CAUTION.)
Step 1: Materials
(1) Pilot G2
(1) sewing pin (make sure it fits!)
(1) small piece of tape, or part of a chip bag. (something thin and strong)
(optional) superglue, extra spring.
Step 2: Disassemble/Add Pin
Twist the pen apart just above the grip. Take the ink camber out and pry the cap off the end of the ink chamber. Next, take the pin and poke a hole in the tube just above where the ink is. This will prevent the ink chamber from becoming pressurized, causing ink to get all over your prized possessions/wood floors.(trust me) Slide the needle through hole in the black cap, then glue (if you have it) the pin in position.(at this point, you could glue the spring to the ink chamber, so that you don't have to search for it when you shoot) Next we take our tape/chip bag, wrap it around the bottom of the pin and put the cap back into place. Reassemble.
Step 3: How to Shoot
First, aim the pen away from anything that you do not want to hit (I shot my friend in the shin once. fyi, it stuck in there like he was made of cardboard :0 ) then put your nail up against the base of the needle and pull back. When ready to shoot, quickly slide your nail off of the ink chamber and fire.
Note: it is almost impossible to fire one handed. I am doing it one hand in the pic because i was holding the camera.)
Step 4: Done!
Congrats, you are done! If you use a needle of appropriate lengh, you should be able to fully assemble the pen. If you like this Instructable please vote for it in the Office Supplies/ Back to School contests!
Also, let me know what you think! any criticism/ ideas would be appreciated. (yes, i am aware that i use the / allot :) )