Very informative, and a great design. My only question is concerning the fan placement. It appears as if the fans are mounted right against the floor and ceiling. Did you space them away from the floor and ceiling to allow air to get behind the fans? If you did space them away, you may want to add a section to your tutorial about how you mounted them. Also, you may want to add to your tutorial, the mounting location of your T-stat, switches, and probe placement in the incubator that has provided you with the best temperature regulation.

Other than a few thoughts of what to add, that is a great job and will provide a wonderful tool for others.

Thanks for the great work,