If you can use a soldering iron there is a electronic kit availabe that I use, it`s cheap and very reliable. The company who makes it is called Velleman the kit number is MK138 and is sold worldwide, although in standard kit form it is wrong for incubator temperatures but if you change 4 resistors and the variable rheostat it works great. I have 2 kits built and they are holding the temperature within .5 c ie max 38c min 37c if anyone is interested I can list the modifications you need to do. The kit requires a 12v Dc power source like a cordless phone charger or similar.