When my daughter was about 18 months old, we went on a trip to an island off of Tokyo's coast called Shikinejima. It was the off season, most restaurants were closed and we were sleeping in a tent.
We ended up doing a lot of shopping at convenience stores, eating meals of: apples, Oreos, cans of hot cocoa, and cans of tuna fish, and were even gifted a fresh bag of assorted seafood from a local fisherman, which we hesitantly attempted to cook over a fire... Maybe you've had a similarly strange almost-camping experience?
One of the shop keepers, a little old man who was so enamored with our daughter and her blond hair, kindly gave her a red plastic 3D heart pendant which had a light inside that would blink on and off.
It was one of those toys with sticking power, and became well-worn and well-loved over the next year and a half- that is until the battery died.
When I saw this cardboard heart ornament on Pinterest by A Little Learning for 2, it gave me the idea for making a low tech replacement for the blinking heart pendant.
My daughter approved. She loves being able to open and close the locket. We're now working together to make something similar as a Valentine's Day present for the grandparents. Definitely not afraid to share the cardboard love....
Info on adding cardboard beads to your locket here.