This project is very much geared towards Christmas Decorations but with a little imagination the technique could be applied to all sorts of other applications.
It's REALLY important normally to not connect anything DIRECTLY to the computer. These LED based lights are designed to work on THREE dry cells (AA Batteries) instead of the more usual TWO. This means that they run on 4.5v which is very close to the 5v that the computer uses. They already have a “Current Limiting Resistor” which is very close to the correct value, so I think I can get away with it, I have not calculated anything! It's a really quick and dirty prototype that works, I haven't had any problems...
Step 1: Prepare your Tools and Clear your Space
Well let's assume you have at least some idea of how to use the tools in the picture. It's not rocket science but hot things will burn you and sharp things will cut you. Be a grown up, take responsibility for your own actions, and take suitable safety precautions.