bassman10096-
Foil is definitely more effective as a shield than the carbon conducting paint that you buy for guitars. The good stuff is equal to foil, but is really expensive ($150+/liter). This stuff has metal (copper, silver, or aluminum) in it and it's what you used to see inside the cases of plastic computer cases (if you ever saw the inside of an old Mac, for instance). It's sprayed in a very thin film, and in more modern electronic stuff that has a non-metal case, it's vapor deposited as part of the case manufacturing process.
Conductive paint is a lot less work to apply and will yield more complete shielding than foil which isn't trimmed and joined around the edges really well.
Aluminum foil should work just fine, but it's hard to solder to the surface which makes for more work or leaks between the pieces.
