Split ring carabiner. I use this to keep my overpants attached to my motorcycle boot laces. loop of shock cord is tied through the closed hole and then i put a horizontal section of shoelace between the split section and when it twists it is locked in place. To quicly remove you just twist it so the laces end up under the hook and then pull it. Would work perfectly in larger scale for rope/paracord as well. I printed it in PETG so it has good strength and enough flex to clear whatever line you want to clip it onto. I had issues with carabiners flexing and popping open in small format for this usage so i ended up with this design.