It looks like you have this WWAAAYYYY under control, but can I suggest painting the the machanical "guts" parts and mechanical joints in a very dark grey -or- black?
This simple step will provide all of the shadow you will need in all of those millions of little nooks. Black or grey will also provide a strong foundation for any metal colors used for the "guts".
Just an idea, it will also save you many headaches when you apply washes to all of the many nooks in the mechanical areas.