Print and use a O-ring to grip the keys. This one works nicely with a 30mm O-ring. This one is for a standard metric set of 1,5-2-2,5-3-4-5-6-8-10mm For any other size, open the OpenScad file, edit and you have your own size. I printed it in two colors just for fun, it is just one printed part + O-ring (or rubber band, or spring) Same function as the original, the scad file has been slightly refactored for easier customization. I added a hole in the middle to hang the whole tool set. I also changed the logic for the placement of the top labels (defined offset from the holes)