What cheap, readily available material could one use to maximize airflow while minimizing the loss of heat/moisture from an otherwise insulated environment? AskEngineers

By otherwise insulated I mean this material would cover a hole in a refrigerator being warmed and humidified.

Submitted April 16, 2017 at 09:01PM by blazingeye http://ift.tt/2pmyeCr AskEngineers