I also use a styraphome cooler as a DIY incubator for duck eggs.getting the humidty right is making me crazy.i have a cup of water with a papertowel to wick up water.. but..
I am using a DIY styraphome cooler for an incubator too. The humidity part is making me crazy. But ducks are still alive in eggs.another week till lock down I think...
Not spraying the eggs either..yet