Mine is made from an old fridge. I use a muffin fan to take air from the top and blow it back into the bottom. A light bulb in the bottom provides heat via a temperature controller. When I am rough turning to fill the kiln, I leave the fan on but turn off the heat. Once it is full, I increase the temperature a few degrees each day until about 80F and keep an eye on humidity level. Once the humidity level starts to drop, I raise the temperature a few degrees each day until I reach 100F. I usually stop there, because that seems to give me stable results. It takes me about 6 weeks to dry a fridge full of bowls (about 40 bowls of various sizes).