FYI, if you have been looking for a fan appropriate for cooling 1/12 ESC with a small footprint,

https://www.digikey.com/product-deta...568-ND/2757798

This is a 20mm x 10mm 5v axial fan. They move quite a bit of air, draw only 0.15 amps, and are almost the same height as a pan car battery. They are $10 each but that's only a hair more expensive than a standard fan, just have to tack solder it in like a touring car.