Temp and Flow Meter for K40 Laser

Based on @TechBravoTN's excellent video on his K40 laser's cooling system:
https://www.youtube.com/watch?v=4jftb_jcTy8

I wanted something similar, but I wanted to completely encase the sensor to minimize stray laser light from shining through the acrylic flow sensor block. (Probably overkill, given CO2 laser light does not pass through most clear materials).

This is meant to double-stick tape to the inside of the K40's laser tube compartment cover. I used a stepped drill bit to punch a