@bonifartius Some ideas:
If buying then:
- Mobile holder / pouch
If making / re-purposing / recycling:
- Old glasses case or old pouch
or anything similar you can put a belt through, glasses case are very rigid and might be too big but clap and close well, else a push-button used for many things
If you have children or place of old stuff / 2nd hand store to look through if might be a fun search rather than buying China as product that might falls apart