Wondrous item, uncommon
This coin pouch tries to prevent anyone other than you from withdrawing from it. It has long, metallic fangs around its opening. The pouch weighs 1 pound and can carry up to 300 coins. It spits out anything that isn't a coin. You can pet the coin pouch, as if it were a house pet, for 1 hour, which can be done over the course of a short rest. At the end of that time, you must drop at least 1 gp into the pouch. If you do, the bag's loyalty shifts to you, and will force any creature other than you to make a DC 13 Dexterity saving throw whenever it tries to gain access to the pouch (such as by a pickpocket or similar). A creature that fails the saving throw takes 1 piercing damage and fails to access the pouch. On a success, the creature can withdraw up to 1d10 random coins from the pouch while avoiding its bite. If a creature other than you is holding the pouch, it releases a dog-like whine until its loyalty is shifted to that creature.
Ask yourself: is the gold worth your fingers?