Patriot Contraptions built a fan holder to prevent fogging in this goggles with 3D printing... "It been a long time since I played with my 3D printer, but its now back in action. The first test project is to build a fan holder for my goggles so the will stop fogging. I got this idea from some paintball and airsoft guys who I talked to about the small fans the had on their masks.

This is made for paintball goggles that are also in use for many airsoft CQB games and limited items at Airsoft Extreme... "The Jt Vortex paintball Fan features a high speed motor which silently extracts hot humid air from inside the goggle and exchanges it with cool fresh air in seconds! The Vortex features a 2-way switch to either blow air in or draw air out of your paintball goggles.