I have read a lot of articles to make pickups yourself. But I am sure the one I propose is the easiest. You have to take an old pc microphone. Take out the machinery from the inside. It is as small as hajmola tablet. Solder (I used cellotape) the wires to the two terminals sticking out of the mic button. Stick the button near the bridge. It would be better if you punch a hole in a 2 inch by 1 inch thermocole and put the thing inside (It gives much more stability). And voila! Your pickup is ready. Plug it in your computer (in the microphone socket).
If you put it below the strings near the bridge, it gives a clean tone. If you put the top of the mic button (Side opposite the connections), into the hole, it gives a distortion effect. Cool, isn't it?
Make sure to stand as far as possible from the pc or a very unpleasant noise appears on turning up the volume (similar to that when a microphone is turned on and put near a speaker).
Enjoy and experiment. I hope you like the idea. Do comment and give reps if you think the article to be worth.