Fantastic stuff David - a great post
I'm starting to think about casting a knob for an old BBC loudspeaker unit that I have a pair of and you've given me plenty to think about. My material of choice for the knob was going to be "Milliput" epoxy putty. It's available in a wide range of colours and I had wondered if by roughly kneading two different shades together a sort of imitation Bakelite might result.
Cheers,
Steve.