We were going to use a styrophoam cooler we had, but then the way we had to put the light in would likely catch it on fire, so we don't want that. sadly, now we have to make it out of wood, which will really mess up the humidity, but i'm hoping to get some insulation in there. how big should i make it for my duck eggs? we'll have quite a bit in there and somehow get a small fan in there, so how big should i make it? any ideas on dimensions?