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I used a large vaccine cooler, because they are really thick and heavy duty. They are also really big, which makes the temperature easier to control than smaller ones. (My first unit used an insulin cooler, which was smaller, and more prone to temperature variations) I have an 8 X 10 glass pane recessed into the lid for viewing. I use a small heat lamp bulb in a spotlight housing for heat, hooked up to a thermostat (the water heater kind) I do circulated air, so I used a small dual computer fan located up at the top of the container so I wasn't blowing air directly on the eggs. In the bottom I have a ceramic heat sink - I have about four 6 X 6 industrial floor tiles taped together in the very bottom. On top of that I have a tray made out of galvanized hardware cloth spanning half the bottom and lined with a terry cloth towel. I have a second piece of hardware cloth dividing the unit into 2 compartments, to make sure no one can get over to the other side when they hatch. On the side without the basket I have a bowl with a sponge which I keep damp to maintain humidity. I have 4 vents at the bottom for air, and 2 on top. During lockdown the bottom vents double as ports for me to inject in more water to adjust the humidity. I also run a digital temperature probe through a bottom port which sits among the eggs for spot temperature measurements. I use a digital thermometer/hygrometer combo to monitor temperature and humidity at a glance. During calibration before each egg run, I set the thermostat about 2" away from the heat lamp housing and adjust it to average 99.5. As the eggs develop and generate heat, I move it closer to the light by 1/4" increments as opposed to changing the setting on the dial, since I can make smaller changes this way. For cat/ferret proofing, I use duct tape. It comes in pretty patterns, and no one can get their claws through it. I covered the entire unit from top to bottom, so they ignore it. Any exposed styrofoam seems to scream "scratch me!!".... I ran the unit non stop from spring until late fall last year, and hatched out pheasants, ducks, and tons of quail in single and staggered mixed batches. I would just bleach between each hatch, re calibrate the temperature, and throw in my next load!