Presentation at the CollABD'07 conference, Rome; proceedings published in "Collaborative working environments for architectural design", edited by Gianfranco Carrara, Antonio Fioravanti, Yehuda E. Kalay, Palombi, 2009. This paper presents the BARCODE HOUSING SYSTEM, a participatory design environment aimed at enabling user involvement in the customization and construction of collective housing through industrialized methods. In contrast to traditional mass production, the system embraces the paradigm of mass customization, allowing users—tenants, architects, and builders—to collaboratively shape housing units via a sequence of intuitive, user-friendly interfaces. By employing visual metaphors, cognitive mapping, and photographic imagery, the system bridges the gap between architectural conventions and layperson understanding, fostering a meaningful dialogue between users and the design system.