How to make rattling Kodama figurine? I want to make a small figurine (about 6 cm / 2 inches high) of a Kodama from the movie Princess Mononoke. They are tree spirits, have a vaguely humanoid body and an oddly shaped head that rattles when rotated. The head is roughly as big as the rest of the body, so it would be 3 cm / 1 inch in my figurine. Here's a short clip showing their appearance and their rattling.
I plan to either 3D print the head as a hollow object or use a small plastic container that I can deform with a lighter. I want to mount the head on a spring scavanged from the tip of a ball pen. But I don't know how I can make it rattle. I was thinking about putting a bead or small marble into the head cavity, but you need to shake the head a lot more than the typical movement shown in the movie to make it rattle. Small beads also wouldn't produce a remotely similar sound to that in the movie.
Does anyone have an idea how to make a Kodama head rattle?
To really mimic that sound experience, I'd recommend using multiple small pieces of something in the cavity. A single piece would have to bump against its enclosure to make a sound, but many objects inside will produce noise against each other as well as the enclosure. (While a single Kodama may actually produce only a small rattle on its own, I rather like the idea of being able to hear the raindrop-like patter of many at once...)

Ball bearings are metallic, but en masse they will have a more &quot;rattle&quot; than &quot;chiming&quot; sound, particularly if enclosed in a non-metallic casing.
Aquarium gravel will give an authentic stone sound. Since the shapes are irregular rather than spherical, it may contribute to the natural pattern that is heard in the linked video.