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.
Reusable zip ties.
Tons of mini magnets and metal clothes pins (infinite bag closing clamps for near free).
My victorinox signature with a pocket clip (keysmart nano clip). It’s a tiny swiss army knife with a built in pen. Comes in handy almost daily an never leaves my waistband otherwise.