This paper provides a comprehensive review of 3D concrete printing (3DCP), focusing on the technical issues and solutions surrounding the process. 3DCP, which uses computer-controlled extrusion of cement-based mortar to create physical objects layer-by-layer, has been under development for over a decade and is currently being researched by more than 30 groups worldwide. The paper discusses the properties of wet materials used in 3DCP, including open time, pumping, extrusion, and layer cycle-time, as well as the hardened properties of the material. It explores how these properties influence the geometry of the created object and identifies key research areas to improve the robustness and reliability of 3DCP. The paper also addresses issues such as layer adhesion, bulk density, tensile reinforcement, shrinkage, and geometric conformity. It concludes with a vision for future research, emphasizing the importance of optimizing component geometries through co-simulation, improving finishing processes, standardizing manufacturing parameters, and developing materials with repeatable fresh properties. The ultimate goal is to enable architects and engineers to design certifiable components and building elements with enhanced functionality and aesthetic appeal.This paper provides a comprehensive review of 3D concrete printing (3DCP), focusing on the technical issues and solutions surrounding the process. 3DCP, which uses computer-controlled extrusion of cement-based mortar to create physical objects layer-by-layer, has been under development for over a decade and is currently being researched by more than 30 groups worldwide. The paper discusses the properties of wet materials used in 3DCP, including open time, pumping, extrusion, and layer cycle-time, as well as the hardened properties of the material. It explores how these properties influence the geometry of the created object and identifies key research areas to improve the robustness and reliability of 3DCP. The paper also addresses issues such as layer adhesion, bulk density, tensile reinforcement, shrinkage, and geometric conformity. It concludes with a vision for future research, emphasizing the importance of optimizing component geometries through co-simulation, improving finishing processes, standardizing manufacturing parameters, and developing materials with repeatable fresh properties. The ultimate goal is to enable architects and engineers to design certifiable components and building elements with enhanced functionality and aesthetic appeal.