Yes, you can purchase humbucker covers from any Seymour Duncan dealer.

Nickel Humbucker cover part #'s:
11800-20-NC for standard pole spacing
11800-21-NC for Trembucker or 'F' spacing

Gold Humbucker Covers Part #'s:
11800-20-GC for standard pole spacing
11800-21-GC for Trembucker or 'F' spacing

Any Seymour Duncan dealer can order them from us for you if they do not have them in stock.