i have a thermostat that keeps a styrofoam chest around 100. Most of the stuff is just junk i had lying around. Its a double edged sword to be a handyman. I cut and inlayed a piece of glass and rigged up an old bulb socket to my cheap ($10) thermostat. the little hotdog rollers are cpvc pipe that can be controlled from the exterior. Humidity can also be altered via a small pipe over an old sponge.
Its my first time and i think my humidity was too high. I fear their air sacs didnt develop well and the shells are super thick. I guess people switch feed around the time they collect eggs for hatching. I know its not exactly permie to have a bator, but i have fun making things like this.
We're handy but also lazy devils, so we let the hens do all the work of incubation, keeping the chicks (hens, ducks, geese) warm and safe and teaching them about life outside the chicken shed ! :-)
My internet has been too shotty to post, but here we go. I got 7/18 hatched. Im making some adjustments after the eggtopsy. Some were well developed on day 24 but with no pips. Perhaps i should have waited but i bet they drowned. Im gonna doen the humidity and put some more holes in for convection. Ill also up the heat a tad. My thermomoeter mighta been a tad off. All in all a successful first time!