I built a defogger for my Skyzone Diversity FPV goggles.
I incorporated an easy to solder on/off switch and a female JST connector. Just feed 12V from your goggled PSU.
Here's a link to the mini 25mm fan from ebay.
http://www.ebay.ca/itm/261166958988?_trksid=p2057872.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT
I bought a cheap dollar store LED flashlight and dismantled it to get the on/off button.
SKYZONE_Fan.stl | 1.1MB |