Don, yes, I`ve seen this in the flesh! A group of our A-level physics students made one and I helped them source the tube. The physics teacher had them using a plastic drain pipe tube wrapped in ductape which was working OK, but they were using it so often that plastic was burning and it was smelling! We managed to pick up a long ally tube that they converted. It worked really well with the signal generator and it apparently helped the teacher teach whatever he was with standing waved. As a none physicist, it was interesting watching it!
