I took a Dynex - 3.125" CPU Cooling Fan and installed it into my incubator. Seems to work great, temp is climbing a bit, need to get it re ajusted. It is mounted to the top, and connected to a 9 vlt battery. Plan on wiring it into heating element, and instailling a switch. I have more if someone wants to trade eggs for fans. Next project, making an egg turner for under 15 bucks. This might be a trick, but I love to tinker.