The Citizen Scientist has an in-depth guide to assist with the “Poorman’s Space Program”. The article details construction of a thermal test chamber for simulating near-space and other very low temp environments. –

There are several simple tests that you should perform on an experiment before launching it into near space. One of those tests is the thermal test in which an experiment is chilled with dry ice to temperatures similar to what the experiment will experience during its mission. There are two reasons for performing a test like this. The first is to ensure the experiment will function at extremely cold temperatures. There’ll be no data returned if the experiment freezes up during its mission. The second reason is calibration. Some devices and sensors are temperature sensitive, and they’ll not perform to the same specifications in near space as they do on your bench top.

TTC for Near Space Instruments on –Link

Halo2 High Altitude Balloon
Halo2 High Altitude Balloon –Link

In the Maker store:
Apollo EECOM
Story of a NASA Flight Controller – Apollo EECOM: Journey of a Lifetime –Link