Look up Fender 'foto-flame' guitars. They were a Japanese series that got a flamed 'film' applied to replicate the expensive flamed maple of some high end products. The film contained the signature wavy grain lines in a dark shade, and then the guitar was painted as usual.
Having seen some up close, they're very convincing.
Wood can also be flamed (literally, with a torch), which (depending on the wood species) can highlight the grain as the rings burn slower than the interstices.
Larry
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