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.
Or make a new size with the Customizer (I never had luck with this in-browser app).
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)