The finish of a wheel-well - I recall my Canadian Air Force flying days. Standing in the wheel-well of a CF100 fighter while doing a preflight walk-around, finish was the last thing I'd call it. The aluminum was inhibited by a sickly pale greenish-yellow Cad-plate substance and the structure was simply the inside of the wing, boxed around to keep the airflow from going anywhere. The machinery of the retract system was very much in evidence, as were the guages we were in there to check. So don't get fancy - it's the gubbinsworks of the aircraft.
Stan