That's a clever use of the overlapping! Really does look like you have an indent right there, especially since it covers the shininess of the underling steel with two separate layers. But what about the silver and red? I suppose he could overlap with a darker shade (add black/grey) and lighten the top? Give the illusion of depth? You're way better at painting than I am, I always go the mechanical/physical way out. With etching using an acid like distilled white vinegar and a car battery charger, it would be quite easy to get depths around a 1/32 of an inch, and not horribly time consuming on that grade of steel.
