Geological bodies is a 2:1 detail study - a prototype for a novel architectural tectonic. 3D printed sandstone is used to fabricate the base, as well as to create a series of moulds which are later used to cast the intricate bronze inlay. The prototype is designed to expand our understanding of the formal languages and tectonics possibilities of additive manufacturing. The tectonics explored here looks to geological phenomena which share similar processes of formation such as sedimentary rock formed through deposition, and liquid magma which seeps into faults and hardens. The prototype depicts these combined materials in a state of differential erosion - enabling a slow reveal of one body embedded within its substrate.