How to Make a Concealed Pen Launcher That Still Writes

Some pen mods that I make will completely destroy the pen "function".  Not true of this mod!  This mod allows you to fire ink cartridges AND still be able to write.  It is so concealed that I was able to shoot people write with this during school.

See....normal pen right?

Just kidding.

Tools of the Trade:
Something that cuts through plastic (Rotary drill, art knife, razor blade, or my favorite: Leatherman)
Pliers
Spring (has to fit inside pen barrel and fit around ink cartridge)

Step 1: Disassemble Pen
If you don't know how to, go to my other post How to Disassemble a Disposable Bic Pen

Step 2: Cut Front Cartridge Holder
 ~This is the step that requires a knife.  I am not responsible for any damage caused to anything (or anyone) you choose to cut with your knife, except for the pen.  If you accidentally slip and cut yourself, tough luck.  You have been warned.~

Take the knife and cut down about half of the cartridge holder.  Save the ring of plastic you just cut off.  This part will take a LOT of time.  So if you have homework to do, I suggest you do your work now and save this part for later.  

Step 3: Reassemble the Pen

Take the ring of plastic you cut off and wedge it into the back of the pen as indicated in the picture. 

 Next, take the spring and drop it down the front part of the pen.  

Take your ink cartridge and also drop it down the front part of the pen.  The back part of the ink cartridge should poke out.  Pull back and let go!