“3ricj” sent in this instructable on how to build a thermal test chamber. Why do you need a thermal test chamber? I’ll let “3ricj” explain:

Getting stuff *really* cold is difficult, dangerous, and lots of fun. Our group is preparing to send an autonomous glider up to about 100,000 feet, so we needed a way to chill our electronics to -70c to test their use before these edge-of-space flights.

Learn how to make your own Thermal test chamber

Thermal_Test_Chamber_int.jpgBuild a thermal test chamber