Custom Paint Match?

[ElBichoMalo]

I haven't done my transom yet, but it is getting closer to the top of the list. My boat already has a great looking paintjob on the hull sides (and transom), so I will not be painting the outside of the hull. The problem is, I'm not sure what was used, what color, etc., so I don't how I will be able to match it after the transom job. I have color charts from Interlux and Awlgrip, and none of the colors are a match.

Is there somewhere I can get a custom color mixed? Would I have to take it somewhere and let them paint it? I would rather just buy the paint and roll and tip myself.