While Charles and Brook Otter were waiting for Patrin, the Toymaker's apprentice, to bring the Flying Fish Car around so that they could continue on their journey to the town of Carousel they watched a young elf boy playing with some Marble Tumblers. He told them his name was Tomi and that he liked to make these little racing toys for his friends. Charles and Brooke had never seen anything quite so charming and they had a pleasant time racing the tumblers down a ramp.
This is the small marble version.
Try adding more than one marble and see which one works better.
This is the big marble version.
Which is faster?