How do those Harmony balls, or Baoding balls, actually work?

The most I've gotten is it's a "sphere within a sphere and there's a bell", but I don't want to cut one of mine open. Is it an ancient chinese secret.? I thought it might be like a rain stick with thin metal soldered to the inside surface with a loose ball to strike them.

rickharris8 years ago
OK found a picture of the inside.
sjzllc004 years ago
rickharris, could you show us some more bigger and clear picture about the inside of baoding ball? The metal rods is called spring. thx.
rickharris8 years ago
I cut one open, inside are a number of metal rods and a ball bearing that hits them as it rolls around. I may still have some pictures somewhere.
SSmithers (author)  rickharris8 years ago
Thanks! That's what I thought was in there, but all the chinese websites made it seem way more mysterious. One said it was a "sphere within a sphere", which can be interpreted as a ball bearing in a sphere. Thanks for sacrificing a ball for curiosities sake.