Quote Originally Posted by harveyje
You can also put the tray in a larger tray filled with water slightly warmer than the desired temp.
I used this method at one time and it works. I used one of the laundry type sinks with an acquariam heater to hold the water bath at the proper temp.

I now have a stainless steel sink that I salvaged somewhere years ago into which I have cartridge type heaters installed in a sump controlled by a solid state controller that does the same thing that harveyje's method does.

I bet his method cost less and works just as well. Did someone say something about reinventing the wheel?