You could take advantage of the fact that stretching rubber bands heats them up, and relaxing them cools them down to build a mechanical refrigerator. Check it

You could take advantage of the fact that stretching rubber bands heats them up, and relaxing them cools them down to build a mechanical refrigerator. Check it out. A refrigerator that works by stretching rubber bands https://www.youtube.com/watch?v=lfmrvxB154w https://www.youtube.com/watch?v=lfmrvxB154w