I didn't think it was that special so I haven't made a thread for it, lol. I just took my 10 years of herpetology/herpetoculture and applied it to my chicken brooding. The thermostat is a (used to be called A-life, now it's like zilla or something) simple dial intended for use in a reptile enclosure. Cant remember the price, but they are super cheap compared to my actual reptile enclosure thermostats. The heating pad is an old walgreens brand w/o safety cut off. It's all the way on high, but if you get a newer one, it gets WAY hot, even on the lowest setting, so I'm afraid that would burn right through the plastic!
Any time you use a heating pad under something, be sure there is air flow around it to prevent hot spots/burning/fire hazard.
If you want a cheap and easy rheostat for your CHE you can buy a lamp dimmer at Lowes where the lamp plug plugs into the Dimmer and the dimmer into the wall. You can also "make" one with a different type of dimmer (the kind you put in the wall) but that requires cutting the cord and reassembling it with the dimmer in the circuit. You would use a junction box to hold all the wires and the dimmer together.
This requires a bit of electrical know-how and is easy but if someone isn't comfortable, it could be a hazard so safer to go with the plug in version.
This way when you need to lower the temperature, you can just turn down the dimmer.
I've been debating on creating a broader using calorique flexxwatt heat tape, but I'm not sure how much of that stuff I have left hanging around.