William Sommerwerck schrieb:

Wouldn't it be possible to make the polyimide conductive by rubbing graphite
into its surface ("The Audio Amateur" had at least one article about
home-made electrostatic speakers that showed how to do this with Mylar),
then plate it?

Hello,

it will be possible to get a nickel layer on the polyiimide if you start
galvanic plating with very low currents and the gradually increase it.
But the problem is the poor fixation of the nickel layer to the
polyimide. The normal pcb material uses a special glue for the fixation
of the copper foil to the base material.

Bye