Simple lens cap clip designed to fit on neck strap - Slides over one end and snugly holds lens cover.
You can also thread the ribbon through differently (I've included an extra set of gaps either side for this) - it depends how snug you want the holder to fit on the ribbon. If you want it to slide up and down easily, thread it as shown in the pictures. If you want it fixed, reverse the threading!
Mine printed with 20% infill and 0.2 layer height on my DaVinci 1.0. No need for supports/raft/brim