This is a 3-D printed piece so small and light that I leave them lark's headed onto my tails and line laundry through the big hole. The hole is large enough to take a swivel clip for spinners. It holds remarkably well even with buffeting winds, doesn't slip, very quick and easy on and off without having to fetch extra bits out of the pack. It holds strong enough for light wind ground stakes and even for mid sized kites with an extra turn. I've tested it to 140# (my weight) without breaking.
Thanks to Darril dela Torre for the inspiration.