Copper Key. Lockable Ideas!

The Copper Key could add another use to copper, while at the same time allowing players to keep their valuables safe. How the key could work is like this: when it is first crafted, the key would be unbound. That key would remain that way until it is bound to a chest, door, trap door, and maybe even Red Stone buttons. 

However, once a chest is locked, the chest and or the key could change design. Also if the chest is mined, instead of acting like a regular chest and dropping everything, the chest could just turn into an item with everything still inside. Having people stealing your valuables is annoying. So why not create some solid security?