A line of plastic fasteners called Kingnut, available from Alliance Plastics, can be applied to a thread by pushing it onto a bolt and locking it in place with a half turn. The device will stay firmly in place, even during vibration, yet is readily removable and reusable. It is made from glass-filled nylon that resists grease, oil, and fuels, and is heat-resistant to 100°C.
A line of plastic fasteners called Kingnut, available from 