I was inspired to make this when I was watching TV one day and saw an Ad for a multivitamin for cardiovascular health that showed a heart made of watch gears. The image reminded me of a book that I read a while ago called The Alchemy of Stone
by Ekaterina Sedia. The main character in the novel was a clockwork automaton who needed a key to wind her mechanical heart. I'm not exactly sure what the heart looked like so this necklace is really just my own interpretation of a clockwork heart (the watch gears don't actually move).