Lerdge-X Stepstick cooler

thingiverse

It's a crude, basic setup that isn't very efficient, but it seems to work okay and keeps the TMC2208's cool. The slots on the front and back have a combined larger volume than the hole for the fan at the top, so it moves air quite effectively. I used the 2-pin power connector at the top of the board to plug in the 24-volt fan. You would naturally want to match the fan voltage with whatever voltage power supply you're using. You'll likely need to enable support.