This is fun. I'd love to build one of these sand courses. Go ahead, pick a marble and watch, but don't pick the pretty pale purple like I did because it rides about 5th place for a while and somehow comes in last! This makes me want to get out my Dad's old marbles and figure out how to play the game of marbles again. I know it takes a chalk circle on the ground.
SORRY! That video seems to have been removed and I have no idea what to search for to find it again. It must have been cool!