Most people use a light bulb and fan. I have been doing some research on it. I have a great incubator a brinsea octo 20, but it makes a bad hatcher, so I'm wanting to build an incubator to use as a hatcher.
I am going to use a Styrofoam cooler, but put a plastic ( or something easily cleanable) liner in it, at least to line the bottom that will get the dirtiest.
Everything I have read says it will be best if your fan / light placement is such that the fan blows over the light and onto the thermostat, they report that giving a more stable heat since the light stays warm after the thermostate cycles it off. A ceramic heat bulb is an option too, but then it will be to dark to see your babies hatch. lol
There are lots of ideas out there for sure.