If you're working with Bob, tell him Gene Kanak says hi! I had the pleasure of working with Bob when we were both at USBC, and he was one of the nicest guys you could ever meet. In any case, yes, those PVC contraptions are cheap and easy to assemble, and you can use them in various ways. Aside from the whiffle ball, I've also seen people dangle pieces of string or nylon straps from the crossbar so that they could practice having the ball touch the string as it travels underneath. It can be a very good tool.