Think about The Da Vinci Code where the clue was hidden in the cryptex that could only be opened with a special word code. If the person you are giving this to wants that gift, he or or she is going to have to guess the five-letter code. That is about 12 million combinations, so start guessing.
Maybe you should leave a riddle, like in The Da Vinci Code, but there is no vinegar involved. The vinegar is supposed to leak into the contents if you try and break the cryptex. So what is stopping the receiver to break the Puzzle-Pod Bank and Present Vault and get the gift? Nothing.
It had better be worth more than that monkey. You can find the Puzzle-Pod Bank and Present Vault on the ThinkGeek site for $29.99.