Retail service shop such as bakery, ice cream, or similar shop, custom tailoring or millinery shop, clock, watch, or jewelry shop, or household appliance repair shop, provided that:
(1) Any processing activity shall be not less than 20 feet from the front of the building and shall be screened by a wall or partition from the front portion of the building used by customers.
(2) Any article made shall be sold at retail from the premises.
(3) The area devoted to processing shall constitute not more than 30% of the gross floor area.