I hope this is the right place for showing my idea of how to store the Coin Case Tags.
The idea can be found at Gambrius Tech Blog. (thanks a lot for all your effort)
This is a great idea for small tags but they can get easily “lost”. Ask my kids 
I changed one of my favorite 3D Print Boxes to store some Coin Tags. This box is amazing and can be used for a lot of things
The inner is printed with TPU. PLA should be fine as well. (no supports needed)
In addition you just need 6 M3x30 screws. There a black ones at amazon
have fun!
