Old fridge, ceramic heating element, temp controller, two computer fans: https://imgur.com/a/diy-temperature-controlled-fermentation-chamber-KuDFu11
Styrofoam box, humidifier, temp controller, humidity controller, perforated hotel pan: https://www.culinarycrush.biz/all/fermentation-chamber
Kitchen cupboard, reptile heating mat: https://www.americastestkitchen.com/articles/6855-diy-fermentation-chamber