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