Pye P123 transistor radio 1957.

[Mike Watterson]

I've used cooking foil.
Damp card pressed to shape with a teaspoon.
Dish foil with teaspoon soft mat.
Glue to card.
Colour with metallic pen or spray.
Trim and glue into knob after removal of old glue. Sometimes I just fill knob with metallic pen.
I just got some heavy metallic craft foils from Lidl to try.