I bought a piece of 1.5 inch stiff foam to try to fix a sag in a bed. It didn’t work but having that thick piece of solid foam around has been a life saver.
Need something flat to put a laptop on? Throw it on the foam. Going to be doing something that requires you to be on your knees for a while? Get the foam!
It went from stupid purchase to something I’d gladly replace if it broke.
You really can’t believe you can put it in a microwave while holding it , but it is genuinely great. A bit long to heat up, but I can’t complain when you get a nice toasted sandwich in exchange.