I had an old computer mouse sitting around that didn't work anymore. So I took it apart and found the chip thing on the inside. I used wire cutters to snap it apart. There were these conveniant little holes where the screws had been, and I used those to string the chip piece onto the wires from the cord. I trimmed those to the length I wanted, and added a jewelry hook.

The earrings were made the same way. And since I hate matching earrings, I made the other one out of a spring from a pen.