Sorry, Tim, I really don't know any more about the Dr. Seuss instruments than I said in my last post. It was just something that was on TV and caught my attention momentarily as I walked through the room, but the program was pretty much over by then. I think it was just an older married couple who had contracted to provide the music for Dr. Seuss cartoons, and built several instruments to do so. Plus they used synthesizers a lot.

For a parade, you can probably get by with improvising on the simple stuff (kettle and trash can lids, for instance). You might want to try hiding real instruments inside of papier-mache mock ups for some of the more fancy things. Also I would suggest plastic plumbing pipe and fittings. It's light, cheap, easy to work, and can be painted to disguise it as metal. No doubt you can sculpt many fantastic wind instruments with it.