Cap cooler

I wanted a simpler cap cooler, uses a 5v 40mm fan powered by a USB battery bank.
I simply put the wire through the hat and down my shirt to a battery bank in my back pocket.

As this fan only uses about 200mA it can run for a very long time even on small battery banks.

Edit: 9/8/19 - I have added a v2 cap clip that holds the fan closer to the cap.

Inspired by [3DModularSystems cap cooler](https://www.thingiverse.com/thing:3721924).