Skin color comes from just three pigments: eumelanin, pheomelanin, and hemoglobin. There are more pigments than that in the paint mixer at the hardware store.
It probably would not be extremely difficult to come up with a way to automatically generate a custom dye mixture that exactly matches a given skin color, out of just blacks, browns, and reds.
It probably would not be extremely difficult to come up with a way to automatically generate a custom dye mixture that exactly matches a given skin color, out of just blacks, browns, and reds.