Macacauba, the wood used for the guitar’s back and sides, can be highly variable – from bright red to purplish brown, symmetrical or with interesting patterns. If you go for a Merlot, you can be sure that you have have a one of a kind guitar.Macacauba, the wood used for the guitar’s back and sides, can be highly variable – from bright red to purplish brown, symmetrical or with interesting patterns. If you go for a Merlot, you can be sure that you have have a one of a kind guitar.