Having figured out the dual-thermistor circuit, I made a small mold from cut-up credit card-ish things, laid down a layer of JB Weld epoxy, and positioned the thermistor assembly just above it:
A generous dollop of epoxy filled in the rest of the mold and it cured overnight:
Extract the final result, file off the rough edges, and then epoxy it to the thermal block:
And then it’s all good!
The thermal resistance from aluminum-to-thermistor seems to be no big deal compared with the thermal inertia of the block and Peltier module.
The Smell of Molten Projects in the Morning 