I'm an electrician so I went a little over board... 17x17x24 plywood box. 24v power supply feeds 2 3" fans positioned behind 2 lightbulbs that are inside 4"stove pipe. 2 lower water heater thermostats control the bulbs. There is a chase behind the fans that sends the warm air to a false bottom with holes drilled in it. I'm testing it with 2 60w bulbs but I think I will have to switch to 75w. I'm keeping it in my unheated entry way until I can convince the wife to let me bring it inside. Turning handle with 2 stop bolts so I don't dump the eggs. 5" observation window.