Aerogel is the world’s lowest density solid, clocking in at air. If you hold a small piece in your hand, it’s practically impossible to either see or feel, but if you poke it, it’s like styrofoam. It supports up to times its own weight.
These are just neat little things I have picked up either through personal experience or advice from other RVers. Veteran RVers will recognize most of these, but hopefully folks new to the RV world will find them handy.