I got a coke machine I set it up with 4 inch wide flexwatt I got it so the tape goes down one side accross the bottom and then up the other side. I use an ESU tstat on the incubator I had a perfect temps once i left it closed, the trick is to have it set up and running befoer eggs are due in case need to adjust it. In my case I had it running from beginiing of Febuary ( going to start it here in a couple weeks as the breeder lone female ( het albino) is unknown when she could possible lay eggs or how fast she go. I got my incubator to take possible 6 clutchs and I don't want that many with out a ready supply of rodents on hand lol.
I found it smart to havea towel ( somme ones) in the bottoem of any unit to asord and mositure that runs down the sides ( which i set so would pull it to the heat tape and be evaporated back into the air lol) I can post pics as I may even play with it today and turn on since can't do much outside with 8+ inches of snow ( snow a 4 letter bad word for me )