In article ,
Kamus of Kadizhar wrote:

I've thought about metallic paint - thinning it and swishing it around.
Something like this: http://www.lessemf.com/292.html . I've though
about electroplating, but that doesn't seem practical.

Most conductive paints will not be at all cheap.

Given your desire for cheapness, I'd suggest that you just use foil and
"ship in a bottle" tooling (grab some coathangers and start bending).
Shove a slug of foil in, and then squish it out onto the walls with long
tools from the neck.

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