To all those discussing RLM02, it is probably my favorite all around color. I am by far NOT an expert on Luftwaffe colors and have seen many furious discussions in forums over them, especially concerning camouflage colors. What I do know is that in general, RLM02 was used as the protective coating for internal components and cockpits pre-war and during the early years. RLM02 continued to be used as a protective coating for interior components through out most of the war, but was discontinued in the cockpits I believe in late 1941 or early 1942, I will let the experts tell you exactly when. After which point RLM66 was used in the cockpits. So if you are building an aircraft from Luftwaffe during WWII you are pretty safe in using RLM02 for wheel housings, engine nacelles, landing gear, and so on. The cockpit will be determined on when the aircraft was made.
*Disclaimer again I am not an expert! Also, it is also true late in the war, for expediency some aircraft were made leaving some or all interior structure bare.