Alright things you need:
Tub
UTH/flexwatt
Aluminum foil tape
Thermostat/rheostat/lamp dimmer
Accurite thermometer with a probe (Walmart)
Start with like, maybe 8 holes on the long sides. About an inch down from the top of the tub. If you don't have a soldering thingy, use a screwdriver that you heat up with fire.
How to set up your tub:
Aluminum foil tape your heat pad under the tub on the outside. Plug the heat pad into one of your controlling devices, lamp dimmers are cheap. Then take the accurite thermometer probe and place it INSIDE your tub, under the substrate on top of the heat pad. Adjust your lamp dimmer or whatever you use as needed to gain a hot spot in between 90-95. Place the accurite unite (shows the temps) into the tub on your cool side. This way you will get your hot side temps, cool side temps, plus humidity.