A small bag that would store coins just for inventory sake that can only story the coins, doesn't do anything other than act like a bundle for the coins only. The cards are still the best form of handling transactions but having to carry a depositor or terminal around to add your coins would be very handy for packs that already have a large amount of items that will take up space.

In my server for instance, the coins are dropped randomly from mobs which means it will take up space quickly after a while.

Thanks!