I'm pretty sure I posted this but I don't see it in my list of posts??? My auto complete filled in the topic and all...
Using materials we had on hand I made this for the corn snake eggs... I used a cooler, an aquarium heater with built in thermostat, glad ware for an egg chamber, a block of styrofoam to float the aquarium heater and an indoor outdoor thermometer to monitor the temps with out disturbing the eggs.
After putting the lid on, the cooler just barely fits in the old fridge we're using to provide extra stability in temps...