In this paper we discuss the development of an interactive, networked, location- and motion-aware instrument for collectively sculpting the urban fabric. Our research interprets the city surface as a ‘thick’, elastic, and permeable medium that responds to the migrational flows of its inhabitants. The mobile artwork Impossible Geographies 02: Urban Fiction explores the subjective, hybrid, and migrational nature of urban geographies. Doing so, it develops a location-aware prosthesis that involves bodies and how they move through space. The mobile instruments become the lens through which to look at and modulate the virtual fabric and its threads. .Its digital landscape presents a dynamic, negotiable terrain that involves multiple authors and produces multiple viewpoints. Constantly resculpting the virtual ‘fabric’ of Urban Fiction, participants collectively weave a performative map of a subjective urban geography.