my best invention was gunwale clips for canoers / kayakers. although no product exists on the market, some lady patented basically the exact thing i was thinking of - a clip that attaches to the gunwale of a canoe or the edge of the cockpit on a kayak that you can clip your paddle into for portaging and shit like that
also, i thought up something really similar to this, but found out it is already a thing...
basically just a lightweight flat-folding fire grate for camping. not as a replacement for lpg/naptha fuel stoves, but an alternative for cooking on fires