2 old ones.....
.... I still use. They're styrofoam shipping boxes ( used a lot here for tropical fish) with a Sunbeam thermometer/humidity guage fit into a cut out. I also use one of those remote temp. kind as a 2nd check. Down here really, we can put the eggs in a closet or something,and they're fine. However,since I have a.c. in my rooms, I use the "incubators" to keep 'em at 82F. The heat comes from an aquarium heater placed in a tall jar filled w/ water. Set up weeks ahead to "fine tune" 'till I get it right. All egg boxes are stacked on top of each other with bottom ones on bricks. It also has about 1" water in bottom for humidity. Keeps mine at 80-100%. They can be doubled in capacity by simply using another of the same size and invert it on the top of the first. Guages are off in pic because I just brought one inside for a photo.