I've had this 'executive toy' -- cunningly called a "tumbling marble race" -- around for a while.
A great birthday present, methinks! (And, sad muppet that I am, it never fails to amuse me!)

It's about a foot (30cm) high, made out of rubberwood, and, according to the promotional blurb,
"the dropping marble tilts each bucket to enable it to fall gently into the next... -- irresistible!"

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Just think, if it hadn't been for the apple,
I could have been famous, instead of Newton...!?!