With our mild winter, I had a chance to finish the paint job on the knee guards. Basically the paint scheme is this:
1) Primer 2) Rusto Aluminum 3) A mix of Valspar Golden Maze and Rusto Pale Yellow 4) Rusto Line Painting Yellow with a mist of Rusto True Orange 4) A touch up layer of a mix of Testor's Flat Yellow and Testor's Rubber 5) Final "grime" layer of Testor's Rubber. (Yes, Rubber is a color, apparently!)
Between each of these layers I used Liquid Mask for the major "damage". For minor "damage" I used a screwdriver and some gravel.