Randy,
Now I'm confused. What knobs are you talking about coloring? The color choices threw me off a bit, because for just a stock supply, my vote would be something along these lines (in this order and for anodized alum):
1. Black
2. Silver (clear?)
3. Red
4. Blue
5. Gold/Bronze
6. Yellow
7. Orange
8. Green
I think purple would be very specific to a setup/particular game IMHO compared to others.
I look at the breakdown like this:
- Black/Silver: Useful on everything, and will work with almost any color scheme.
- Red/Blue: Most prevalent in Cab color schemes, will work with many other colors. (i.e. blue with a purple cab, etc.)
- Gold/Bronze: Again, metallic and will match anything with gold/bronze accents.
- Yellow/Orange/Green: Should match the majority of cab color schemes to some extent, including classic cab retrofits.