So this time you'll be able to find out how to do a natural metal finish. You probably already know that is very difficult to get a natural metall finish look on the plastic model. Some modellers use metal foil to get as natural as metal can be ;)
Ok, less talking - more action. Here're some excellent pics of the build Mustang P-51C in 1/48 scale (Tamiya) with some minor modifications.
Here's another great sample of Natural Metal Finish. This time it's P-47N1/48 built from Tamiya's kit with some serious modifications and "plastic surgery" ;)
Here's how the author describes his method of doing Natural Metal Finish:
"Hybrid Painting Method" for natural metal
This method is hybrid of airbrush and brush painting. First, Mr.color's Super Metallic Chrome Silver was sprayed (slightly mixed #2 black). Second, Mr.color's Chrome Silver (straight from the bottle) was drybrushed on the sprayed surface. Drybrushed silver can express hairlines on the natural matal surface. Detailed painting method is as follows.
#1000 surfacer -> #8 Silver (for the base) -> Chrome Silver + #2 Black (spraying) -> Chrome Silver (drybrushing) -> #46 Clear (spraying) -> Markings(Yellow, Olive Drab, Insignia, etc) -> #2000 sand paper polishing (only for marking portions) -> decals -> #46 Clear & #30+46 Flat Clear (only for Olive Drab portion) -> weathering
(Quote from this article)