You, the Washoos masses, voted (3-0) and the washers have now been painted.

First they were sanded using a 50-grit sandpaper to scruff them up and enhance paint adhesion.  Then both sides of the washer were given 2 coats of spray paint.  The colours are neon green and bright orange.  4 of each of course.

Anectodally, I can report that they are much easier to spot when collecting from around the box (I had to intentionally miss the box in order to check this).  The feel of the washers is slightly smoother but still has a little stickiness so that it feels good in the hand.

I have not collected any empirical evidence as to change in mass, aerodynamics, bounciness or estimates on how long the paint will last.  When I retire and have the extra time, I will look into that.