I make them out fishing leader material (usually 30 or 40lb since I use quite a bit of it and it’s always at hand) whenever I know a tool (knife, screwdriver, wrench, etc.) will be used in or around water... not in lanyard configuration but as a loop to go around my wrist for retention purposes... It’s a very bad feeling losing a valued tool to the salt (which I’ve done on more than one occasion). I even have a brand new full sized Benchmade blade kept on my skiff as an emergency backup that already has a mono loop installed...