Hey Mike, great job on the painting and trimming! I figured out why your grey doesn't look so clean. Humbrol paints NEED to be shaken, and then stirred to get the pigment mixed in with the base really well. Shake the little jar for a minute, then open it and stir it up some more with a toothpick before dipping your brush. You'll be amazed at how much better the paint goes onto the plastic.
As far as the vocoder, you should be using the semigloss black (or satin black)... That looks really shiny, are you sure you're in the right jar? (:
Positioning of the mic tips looks great!