I've been doing some experimenting lately. I don't really plan on doing a relic guitar, but I was just curious about some different methods. I tried a mixture of coffee and pipe tobacco on some cream plastic parts, but that did nothing. I then tried some strong black tea. Again, nothing. I have yet to try a solution made of cigar butt juice (that sounds so appetizing, yum!), but since I do enjoy the occasional cigar, I may try that next. It's really just curiosity with me, though. Oh, I did have some success with white vinegar on some nickel-plated pickup covers. I had to use some Scotchbrite on them first, just to get a the surface a bit more conducive to aging. It did work, but I think I used the Scotchbrite a little too liberally. Oh well, it's just for fun.