Since some of my eggs or in the incubator already, and i have a delivery of 12 more the end of the week. I have now realized that its not wise to add the eggs, due to the humidity change on the 18th day. I thought id have a go a making a hatcher or an incubator myself. But do i NEED to have a thermostat? I was thinking along the lines of a polistireen box, 40w bulb conected to a dimmer to control the heat do you think this would work? Would i need a fan? what the differance in performance between a still air and a forced air incubator? Many thanks