Back when Dale Clemens had a rodbuilding catalog, they used to sell pigments that you could mix in with their Crystal Coat epoxy. You would then give the blank a thin coat of this epoxy. The resulting finish then has the color you want and the durability of epoxy. I used these a few times and had good results, as long as I was putting a dark color over a lighter colored blank. I'm not sure if any products like this are available currently, but you might look around.