How big of an incubator will I need

[Egg_newton]

Ok guys, I am fully hooked on chickens and want to build my own incubator. I see a lot of ppl have had success with using styrofoam coolers. I want to build one that will hold about 25 chicken eggs. How large of a cooler will I need that will hold the eggs and all of the other equipment needed.

 

[Mahonri]

Shouldn't need too big of a cooler for 25 eggs.