I've had professional-looking results with Krylon Fusion.
However, AFAIK, the MacBooks use the same polycarbonate material used in the iBook G4s, so you can likely boil the casing in RIT fabric dye.

I did this with my iBook G4 and will find another to work on, so I can create a guide.
“Creative ability is best displayed with the most basic tools."

Website Facebook Twitter House of Hackers