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.
Maybe not stupid, but I purchased a pair of bone conducting headphones just because I thought they would be better for running, and harder for me to lose. I wasn’t expecting much, but damn, they have been so much better than I expected. Even though the sound quality isn’t quite as good, they work so much better with my sensory processing issues, and I can just leave them on all day without concern. Because I’ve got curly hair, people don’t even know I’m wearing them, and because they don’t go in my ear canal, they don’t impact my ability to hear/talk/interact with the world around me.