There is a simple way to build this thing. Some years ago I built a small version of this at the Children's Discovery Museum of San Jose. Basicaly I made it into a big pinball machine using an inclined board, 4" long hex head bolts, washers and tennis balls. Kids could shoot the balls to the top center of the board where they were released. As the balls fell they hit the bolts which were appropriately spaced. The bolts caused the balls to deflect and individualy be unpredictable as to where they would fall. The washers made a ringing sound. At the bottom where the balls collected there were a series of bins which allowed the balls to stack-up in rows where they came down. It really wasn't quite big enough to show a smooth curve but could easily be made bigger. On a bigger one the balls could have been "cranked" up on a conveyer belt. This is one simple way to make this thing. Joe Ruggiero