This paper reports on the final stage of a summer long in situ research project with the realization of a full scale, architectural prototype taking place in Genk, Belgium 2017. The scope of this project was to develop new ways how recycling of domestic plastic waste can lead to the production of structural elements for an architectural application using the common format of a brick. Appling recycled polymer composites as a building material will reduce waste and elongates the life-cycle of a challenging contemporary resource. The present paper describes a novel strategy for the assembly of an 8m high masonry arch, consisting of 614 bricks. The structure of the arch is designed to take optimal advantage of the relatively favorable compressive resistance of its material. “In situ” research, allows designers and builders to have a continuous exchange within a material-based investigation. Experimentation and craftsmanship complimented with digital and empirical testing, are fundamental to reach an open and accessible construction strategy. The Arch illustrates the potential for the further integration of recycled plastic into the architectural workflow.