Talk:Jet Pack/@comment-5902492-20180521062926

Carbon dioxide extinguishers do this when you trap the exhaust in a bag, like Ed's pants, as the gas expands it cools very quickly, and if it is concealed, you end up with accumulated dry ice.

The King of Random, of all people, has a video demonstrating this behavior, which is perhaps the most cost ineffective way of getting dry ice. https://www.youtube.com/watch?v=tLNHDxd6nDc