I had the idea of making a pointing device shaped like a pen, so I combined a mouse with a wooden stick. It was messed up, but much better at drawing pictures!
What you need:
Cheap mouse (any kind will do)
Take the mouse apart. There are usually little screws on the bottom. If you take all the screws out and it still doesn''t come apart, look under the stickers. Leave the circuits on. Just take the top off.
Step 2: Mess with the circuits
Some parts are not nessacary, like the scroll wheel, and should be taken out. It gets in the way.
It also makes a good spot to put a stick in.
Step 3: Clicking buttons
You can put the left button on the pen. Just find the bottom solder parts the switch is connected to, or use pliers to rip the switch out. Solder another switch with two longer wires. Do not solder over any other connections!
Step 4: Add the stick
Carve a small stick that fits in your hand comfortably. It is a good idea to file down a rectangular block of wood, so you can attach a hinge to the bottom of the mouse. The hinge allows the user to shift his or her wrist angles. Stick the switch on a good spot of the stick where you can press it without getting in the way of writing. Stick the hinge to a uncluttered spot of the mouse base.
This is a crude, but awesome tool for drawing. Perhaps a better pen in the future!