My CZA came out of box in a sheen finish; not dull, not shiny. As Bob says, the factory finish is around 1000 grit.
If you modify the cover by hand, I'd recommend using ScotchBrite pads. If you're experienced with using a ball spinner, I don't see why you couldn't use either sandpaper or SB. The N'Control coverstock is simple resin, not particle.
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seadrive
Cogito ergo bowl