3D printing of cementitious materials has been evolving rapidly, aiming to revolutionize the construction industry. From the production standpoint, this construction method can reduce manual labour and waste by using robotics and eliminating the need for formwork. From the design perspective, it allows geometric flexibility that facilitates the design of optimized structures, exhibiting significant material savings compared to traditional construction. Nevertheless, the limitations of buildability – that defines which components can be built accurately by deposing cementitious material at its fresh state – call for the development of holistic approaches that seamlessly integrate structural optimization, material design and robotic fabrication. For structural optimization we extend our recent work on shape and topology optimization of prestressed concrete. The method integrates shape optimization of prestressing cables – modelled as B-spline curves – with density-based topology optimization of concrete, enabling novel design configurations of 3D beams and plates. A special filter enforces concrete cover around the cables, creating a coupling between the two sets of design variables. The optimization problem formulation mimics the design intent of prestressed concrete structures. Results demonstrate material savings exceeding 30% compared to traditional solid prestressed members, highlighting significant potential for reducing embodied CO₂. To realize these optimized designs, we develop a computational procedure that splits them into 3D-printed parts and cast parts, with the former used as a formwork for the latter. This includes segmenting the whole component into smaller units that can be printed and subsequently assembled. The toolpath for each segment is determined such that it is buildable at the fresh state, while its geometry respects that of the prestressing cables to ensure precise placement and integration. To guarantee buildability, the parameters of the material mix and of the robotic fabrication enter the formulation, creating an integrative framework comprised of structural form, material mix and robotics.