re: #17 Jay C

ISTR a few years ago, seeing a news piece on a carmaker (Honda?) experimenting with a noisemaking system for electric vehicles. Not excessively loud, just a sort of mechanical “whoosh” that kicked in (via external speakers) when the car was in motion, and was just loud enough to let you know there was a vehicle there. Which I thought was quite handy (I’ve had a couple of near-misses in garages): but I always wondered why it hadn’t caught on.

You could always use clothespins to hold a playing card in the spokes.