Step 1: Remove the fan unit from a computer power supply

Step 2: Cut the four supports for the fan and discard the surrounding frame take care not to cut the wires.

Step 3: Remove the top connector from a flat 9V battery Discard the rest of the battery.

Step 4: Place some double sided tape on the fan

Step 6: Colour the circle of cardboard and attach to the fan

Step 7: Solder the battery connector to the fan wires making sure the red wire goes the terminal at the top in the photo at step 3.

Step 8: Attach the battery clip to a good battery.