ken, i tested a small drink cooler last year, it was a countertop model that you see in stores like fasmart, etc. it was about 30 inches tall, and it did swing temps when the door was opened. depending on how big your eggbox is will come into play too. the bigger the eggbox the more thermal mass to help keep temps stable. you can use bottles of water also as thermal mass. alot of guys cut a window into an old fridge to view alot. this year i decided to turn a closet into a "bator"

vaughn