We spray paint everything (except extrusion) on
our robot either MOE Green or Black. We don't have the equipment in shop for powder coating (although we could probably send parts off to have it done). The paint holds up very well, especially since bumpers have become the norm. Our primary spares are usually painted, as well as any Fix It Upgrades. Even in the MOEhawk year when we routinely broke the wings, we had tons of panted spares. In previous years when the paint has scratched, we have touched it up with Sharpies and nail polish.
I wish more teams would paint/powder coat their robots. Bumpers and side panels are great for adding color but there is something special about seeing a robot that is saturated with color. It stands out and becomes part of the team identity. It gets a little monotonous watching a bunch of bare aluminum robots driving around (especially before bumpers).