Chiming in, I wonder if there is a good way to make non-replaceable rubber pads conductive again? E.g. for TV remotes and similar things where the membranes are unique and the rubber is not covered by plastic.
I once tried applying aluminum foil with superglue on the contact area of an original SNES start/select button membrane. It worked very well, but lasted only a few hours since the foil went off again by itself.