After using a chicken egg incubator for the last 2 years I wanted something with more capacity. So last summer at HAS I bought a double deep polystyrene hivebody from Modern Beekeeping. It gave me the insulated cabinet to turn into an incubator.
I mounted a Ranco electronic temperature controller on the outside of the bottom box and used it to run two 40 watt light bulbs as a heat source. I mounted a small fan inside to provide air circulation. I had a piece of 1/4" aluminum plate bent to form a stand over the lights to serve as a heat sink. It also gave me a place to set a dish of water for humidity.
The top box can hold 12 cell bar frames with 45 cells each to give me a total of 540 cells at a time if needed.