After several attempts to make a "show and tell" picture on different surfaces with the "Chrome Pen", I went with the actual plastic trim ring that goes on top of the Rally Pac gauges, inside the outer ring housing.
The red arrow on the right points to the ring, the only part seen from the outside. The red arrow on the left show what was not "chromed", a "before" the treatment, and that is not visible when assembled.
What was also learned are: the surface must be clean and dry; a rough surface will fill up with the ink, so do those first, let the piece dry, and add a second coat (or more); smooth out the ink as you apply it. The ink drys quickly so let it. Don't "test" - (aka push your luck) - it. I don't know how this ink will wear over time.
Jim