The tello is known to get quite hot whilst idle. If you’re programming a flight, setting up a wifi extender or doing any type of development/inspection you would of experienced this.
PC case fans are cheap and the right size for a tello to sit on.
I took the power leads (black and read) from a USB cable and connected it to the black and yellow cables on the fan.
Very easy to setup and you can run it from any USB port like a power pack.