I had an extra drawer in my dresser and put a layer of towels on the bottom. I then set my little iguana heat rock in the middle and arranged my jars around it in a circle. I then covered everything with another towel and kept a remote digital thermometer in there. I was able to watch my temp without opening the drawer. Temps never went above 85. I rotated the jars like once a day to distribute heat evenly to all sides of the jar while it colonized. It's not the best way but it works.