A Geocaching coin you can personalize. I'm making it public on Tinkercad so you can change the text. Don't forget to change the edge writing too as it says "Oregon" and I doubt you all live in Oregon :)
https://www.tinkercad.com/things/lwGLtlHYa3i
Here is a round box to store 15 of them... http://www.thingiverse.com/thing:1612020