Recent debates around urban encounter, integration cosmopolitanism, and renewed engagement with contact theory have raised questions about the spaces of interaction that may enable meaningful encounters between different social groups. Reflecting on a participatory art project with young people of African and British heritage in northeast England, we argue that discussion and practice around participatory action research, including the deployment of contact zones as theory and method, can cast some light on what fosters transformative spaces. Through analysis of two different approaches to community art used in the project, we show how elements of each enabled and disabled meaningful interaction between young people. We draw attention to the materiality of art (the tools) within participatory practices (the doing of it) in contributing to a space where interactions might take place, emphasising a complex interplay across/between actors, materials, and space that frames encounters as emergent, transitory, fragile, and yet hopeful. We examine the potential of a focus on the material in thinking beyond moments of encounter to how transformative social relations may be `scaled up' before considering the implications for research and policy.