I will show you how to make an ink cartridge gun out of a bic round stic pen, some sturdy tape, and a water balloon.

Step 1: Take Apart the Pen

First, pull off the writing part by grabbing the pen at the back, and with your teeth, grab the pen where it starts to taper. pull it out, and once its out, take the tapered part, and ink cartridge first, hit it on a desk until it comes out. now, you should be left with a writing piece, a grip thingamajig, and a blocked off tube. take the writing tip and insert it, ink cartridge first, into the blocked off tube. hit the writing tip on the desk by holding the tube. after a few hits, the end should pop off.

Step 2: Firing Mechanism

take the balloon and put it over the tube, so that there is some loose balloon. take your tape and wrap it around the tube, taping the balloon to the tube.