[en] For the three macromolecular crystallography beamlines of the Swiss Light Source, a new unified diffractometer – D3 – was developed. We present details of the engineering and implementation of the project components that were fabricated in-house by the design facilities of the Paul Scherrer Institute (PSI). Key components of the diffractometer project were custom designed at PSI including a microspectrophotometer for sample viewing and optical spectros-copy and a combined Köhler and spectroscopic illumination lamp. In addition, all elements for beam steering and shaping such as an exposure box and multiple articulated elements for beam shaping and beam diagnostics were designed in-house. Further components are the positioners for cryo-cooling devices, and an X-ray-fluorescence detector. For minimization of vibrations, a combined mineral cast and granite block design was employed for the diffractometer table. Due to the restricted space of the sample environment, a high degree of integration of the D3 instrumentation had to be achieved. Devices to be considered in the integration concept are the robotic sample changer, the area detector and the new multi-axis goniometer PRIGo. Optimization strategies include kinematic simulations to describe the kinematic hull structure of the sample positioning and to reduce possible collisions. Additionally, flexure designs were used to allow adjustability while satisfying space constraints.