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Thin paperboard/cardstock/plastic washers under the nut on the pot for a high contrast writing surface (used like a washer)...or be really cool and machine some sweet dial arrows that pivot out of aluminum and put those as washers around the put shaft.

But I do the set and forget thing.

Permanent markers and solvents will mess with paint or silk screening. Bare metal is fine.
I recommend a China marker (grease pencil). It will rub off without solvents, but needs friction.