This paper describes an approach of a process-aware exploration of the design space of building components constructed by extrusion of cementitious material (or concrete 3d printing). In an attempt to broaden the geometries that are being printed today, and to build cantilevers, vaults and domes without using temporary support, we look back at construction techniques used in masonry structures, and analyse the stability of the fabrication process at the scale of the brick, the layer and the final structure. Those strategies are applied to 3d printing with regards to the material properties and the technological aspects of the process. Three examples are actually printed to validate the approach, namely a Nubian vault, a dome and an arch, all without temporary support. Finally a framework for generation of printable geometries and corresponding toolpaths is proposed.