This is a way to repurpose old computer fans as well as USB cables. I'm using mine to cool down an audio reciever that has a tendency to overheat

Step 1: Stripping the USB Cable

First you take wire cutters or scissors and cut off the end of the USB. Try to cut it as far towards the end this way you have more wire to work with. You then take wire crimpers (or scissors if you are skilled enough) and remove the outside covering of the wire.

Step 2: Stripping Individual Wires

Inside the USB cable you will see a red wire and a black one. There will probably be others like white or green, but those dont matter so you can cut them off. Some USB have a white wire as the negative and gray as positive, but those are less common; most have red positive and black negative. You want to strip the coverings of the positive and negative wires just like before.

Step 3: Stripping the Fan Wires

The fan will probably have some sort of plastic at the end used to connect to the computer, but that is no longer necessary so you can cut it off as well as any wire that isn't red or black. We then strip the wires again.

Step 4: Connecting the Wires

Next you take the red fan wire and twist it onto itself so the metal wire spirals and straightens into one wire. Do that with the black fan wire and both the USB wires. After all the wires are twisted on themselves neatly you take the black fan wire and twist it with the black USB wire. Do the same with the red wires. Wrap the red and black wires in electrical tape SEPERATELY so the red doesnt touch the black and short out. You can do this with multiple fans onto one USB like i have.