So many kids have a fascination with keys that lingers into adulthood. Maybe it's because they are associated with treasure boxes and represent possibilities. At any rate, I am one of those.
This big steel ring came with my house when we bought it years ago. It is loaded with skeleton keys that fit all the many doors. I have always looked at them and thought of Bluebeard's wife with the ring of keys, one of which he forbade her to use. It's a very creepy story that stimulates my already over-active imagination. I added a tin whistle to the key ring years ago to take away from that and add a whimsical counterpoint.