If you look carefully in the SuperPID documentation, they mention the fact that you should add a heatsink to it. They have a piece of metal glued to the board, and you attach your heatsink there. If I recall right, they also mention, or was it them answering my question by mail, that you should have a some airflow if you put the board in an enclosure.
My enclosure was 3D printed, and within it, I got a small MeanWell 5V AC-DC power supply and the board. I’ve added vent holes in the case and a fan to pull air out. Having no use for the thermal probe, I’ve used it to monitor the temperature within the case.
Whatever material you want to use to enclose your PID, make sure it has decent airflow, and a steady 5V current inline.