Incredibly simple 2kb tweak to Spoonail's Self-Recording Thermometer which changes the recipe from needing any metal nugget to needing cupronickel specifically, turning it into very basic Jonastech.

While not required, this tweak was made with Rot Lot Loot in mind since it adds cupronickel bits to the loot pool. You'll still need to brave the caves or the storms to get the bits for your thermometers.