Last week I fond some old plastic Joe Birl rhythm bones on Ebay in perfect condition and inside their original packaging. They came yesterday and I was able to remove them without damaging anything. I HAD to try them!
They have a grove at the top of the bones to keep them from sliding out of your fingers, a unique design to which Joe Birl held the patent. Although smaller than I would have though (6×1 inches), they have a nice feel and sound. I’m impressed and immediately regret the days when these could pretty much be found at most corner stores…
The Rhythm Bone society has put the story of how Joe patented these bones on their website.