I would love to add metadata to every item of a specific itemstack to identify the items. Currently I have to identify the items by adding lore or stuff like this. But I don't like to identify objects by string and therefore it would be cool to add metadata to items of an itemstack.

In addition it would be cool when the metadata still existing when pick up the item after dropping it from the inventory.

It would help to create inventory GUIs when same items (material) should execute different actions.