The Coin Purse can be a vital tool when playing with multiple coin-based currencies. It allows you to stack up to 256 coins in a single inventory slot
To use a Coin Purse, you have to right-click on it in your inventory while having some coins selected, akin to the vanilla Bundle.
To retrieve coins from the Coin Purse, either right-click in your inventory to retrieve up to a stack of the coin type you last inserted, or use it in-world to completely empty it out onto the ground.