Here I will show how to convert a pen and some other ordinary household objects into your own secret water pistol.

Step 1: Tools and Materials

Here is what you'll need:

a pen (preferably bic ultra round stic grip)
electrical tape
a ball pump needle
a drill (or you could find something really pointy)
a paper clip
and needle nose pliers

Step 2: Taking Apart the Pen

First, take apart the pen. The back cap might be tricky so you might need to use pliers.

Step 3: Fitting the Nozzle

Next, take the ball pump needle and try to wedge it into the tube part of the pen. It will be very tight, and you will probably need to file out the inside with scissors or something.

Then, you cut the needle down to about a quarter inch. You don't have to cut it if you don't want to.

Step 4: Drilling the Hole

Next take the back cap and drill a hole in the center of the cap, about the diameter of the paper clip wide. Or you could just poke a hole with a pointy thing.

Step 5: Assembling the Piston

To make the piston you first take your paper clip and unfold it with you pliers. Next you create the handle using the pliers. Then you slide on the back cap through the hole (make sure its facing the right way). Next you wrap the tape a quarter inch away from the end of the paper clip. Wrap around once, then take the quarter inch of paper clip and crimp it down with the pliers so that the tape doesn't slide off. Then finish wrapping the tape until its a good size to fit the pen tube.

Step 6: Putting It All Together

Finally, slide the piston into the pen tube, and lock the back cap back in place. Make sure the piston creates a water tight seal with the pen. You might have to add or take away some tape.

Step 7: Loading and Firing

To load , fill a glass or something with water. Next, pull back the pistol to suck up the water. To fire just quickly push the piston forward.

If it doesn't suck up any water you probably need more tape on the piston.
To have the maximum amount of water storage you should try to make your piston as long as you can.