The device electronics and PCB are so tiny that I had imagined you would be putting them into a shell that was only just a hair bigger.
Ultimately that's the plan, but, as I said, you can see in the photo showing the rough turning the tool I used to 'cut' the profile - a file with a flat and a partial round side. When I get back to my workshop I'll be able to turn a decent piece out of a properly thicknessed piece of wood.
Would it make any sense to give it a larger air gap all around to mitigate effects like thermal mass and/or self heating? Or are those likely to be so small that it doesn't matter to you?
I don't anticipate a problem with this, certainly not self heating - this thing draws virtually no power! The sensor is an SI7021 which you can see pretty well in the Cherry photo (U2) and it's positioned so that normal convection airflow will affect it. I want to measure room temperature and that includes the walls. I don't need instantaneous response.
Also, am curious: if you ever needed to reprogram it,
Why would I need to do that?
would you be using OTA wireless upload programming , or as during development do you have a jig with pogo-pins that fits into the depression for it to physically dock with?
For the moment, it'll be pogo-jig reprogramming until I get Joe's bootloader... The module is only friction fit into the back cavity so pulling it out to reprogram is trivial. The package worked out pretty well in this regard. The PCB is 26mm diameter, but leaving the holding tab 'residue' on the edge of the PCB allows it to friction fit into a 27mm hole. So the wooden piece is drilled to 26mm in the front and 27mm in the back leaving a ring that acts as a stop when inserting the PCB from the rear. Cutting the slot for the antenna wire was easy with a thin pull saw.
I should have mentioned that the pictures show a magnetic clip holding the end of the antenna wire - that clip is simply attracted to a drywall screw in the wall. It turns out, with the thin cavity behind the battery (and the fact that the magnet sticks to the battery), I just need a small super magnet to attach the unit to the wall without needing the clip. A 15mm diameter magnet will be perfect!
Tom