I like to give my players handouts. For consumables, using cards is more convenient than recording every little thing in their inventory.
When keys are important to progression through a dungeon, or when the party finds that mysterious key that might not have an immediate use, It’s helpful if the players have a physical reminder of the object.
Here are some of the keys that I have created for use in my sessions. Perhaps you’ll find use for them as well.
You can also find these keys as cards on Go Deck Yourself.