I am guessing you want the natural metal highlights ??
from a sign painters approach, I would spray paint the whole knob
with Rust-Oleum automotive primer, then gloss black. 2 or 3 light coats of each.
wait 24 hours – then glue some wet-n-dry 320 grit sandpaper to a small flat board (1"x4"x1/4")
and gently sand off the paint on the raised elements under running water.
Glue 600 grit to the other side of the board to poilish it up to shiny aluminum letters.
you will be surprised at how easy it is – – – then do your other knobs to match.
of course preparation is the key to any good paint job: clean, degrease, vinegar etch and paint.
I have some 1/2" MDO plywood sign material that I glue a full sheet of 320 grit paper to one side
and 600 grit to the other side….. after rolling it down smooth and solid, I run it through the
table saw to make different sizes of sanding boards. cheap and very effective.
1.5" wide x 1/4" aluminum flat bar cut to the desired length is the best.
if you need some round sanding blocks, glue the sandpaper to pieces of PVC pipe of different diameters.
another trick is to use 2" square aluminum tubing – then you can have 4 grits on one block.
when the paper wears out, just glue another sheet on top of it. (3M spray glue).
Here are some of my sanding blocks.

if you mess up – repeat the process.

if you want black background with gloss white letters, I would suggest a paint pen.
available at wal-mart, staples, jo-ann fabrics, most office and craft stores.
they come in fine, medium, large and bold tips. Oil based paint in a pen.

.

Charlie,

Lets see it when you finish if you don’t mind. I have a few I might try.