Your DYI looks good. Did you put a fan in it? My lower levels usually run a little cooler but heat rises. I have an older sportsman cabinet. We have a small guest apartment behind our garage that I have used as a hatchery but prior to coronavirus we had company so I put everything in the garage and have been hatching out there. I covered the cabinet with blankets because of the temperature swing between the day and nighttime temperatures in the garage. So far so good and it's been holding well. I recently had a couple of hatches and have another hatch tomorrow. I just checked and I have some pips. These eggs were in the bottom tray. I don't hatch in the cabinet, I only use it to incubate in and I hatch in my old styrofoam incubators. Good luck and have fun...