[Revolution]

Hi all

I'm new here and i'm looking for quite a specific material or how to make it.

I need something that will expand in warm temperatures above freezing and contract below freezing, it would be nice if you could achieve 50% contraction/expansion.

It's to be used in size of 2" x 0.5" x 1.25", rectangular shape 1,25" thick.

Please suggest where to start looking, thank you.

Edit: It needs to be quite durable - might be soft but not break or tear under pressure (being run over by a car/lorry) while the material is fixed in a small pit.