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.
Amazon has a bunch. If you keep looking, you can find a lot that look almost identical but have wildly varying prices and I couldn’t tell the difference between the expensive and cheap ones. Just search manual coffee grinder and go for one of the metal only ones. They look like pepper grinders with a metal crank on the top. I got one of the cheaper ones (around 30 CAD iirc) and have been happy with it.