white fill in on 4WD shift knob?

[curmudge1]

Has anyone done any white fill on the diagram on the 4WD shift knob, to make it easier to see?

I'm thinking about getting & using a white sharpie. But if anyone has a better idea, I'm open to hearing about it.

Aftermarket knobs look nice, not sure I really want to spend money on that item.

Thanks.