Is this for the fiddle you are going to be playing? It's got to be functional and not just cosmetic? If that's the case, could you just sort of 'decorate' the exhisting peg? Perhaps whittle the thumb grip into a crude hinge-joint and just paint a light wash on the outer areas that don't come in contact with the fiddle? I wonder if you switch woods, how consistent your tuning would be. I'm sure your fans would rather hear the good song than get the gimmick, ya know? *g* Cool idea, though. I gotta see my luthier today, I'll ask for his recommendations.
~JE