Reminds me of the days in the school yard we used to set up marble rolls,they were about the same size with lines drawn into the dirt and we would put a grand daddy bonker down the bottom and if you could hit it you would win 10 marbles if not you lost your marble spent what seemed like hours perfecting little grooves and recovering with fine bulldust to divert their marbles,i was on a good roll till the school outlawed the practise.