The 3-4-5 Mailbox Design features a tall, narrow, and deep structure, resembling books neatly aligned on a shelf. Constructed from black powder-coated steel sheets, it is paired with polished stainless steel doors that include transparent acrylic windows and white labeling cards for clear identification. Available in configurations of 3, 4, or 5 pigeonholes, it allows for adaptable installation by positioning multiple units against a wall. The design evolved from the 1975 'A Sardinel' concept, inspired by bricks in a wall or an encyclopedia on a shelf, forming a cohesive and orderly arrangement.