Model originally uploaded to Thingiverse at https://www.thingiverse.com/thing:4971307.

This is a cooling fan setup for the cr-200B that I have. The extruder gears got too hot and with this setup I cool them with a fan. The design can be easily clicked on and of and that makes swapping filament more accessible.

The fan is a E3D Ventilator | 12V | 30x30x10 mm. It fits in there without glue but you can make it more solid with some hot glue on the sides. I have a 9 Volt / 2A power brick with a splitter that I plug in to activate the fan.