The XEUS petals encompass the optical bench structure of the stand alone X-Ray Optical Units (XOU) based on the high performance and light weight Silicon Pore Optics technology. The performance aspects under consideration of the design drivers, the related trade offs (e.g. mechanical concepts, material selection, XOU butting efficiency etc.) and the current development activities wrt. the design, manufacturing, assembly and the functional and environmental test verification approach of the Form Fit Function Model are described in this paper. Special emphasis is given to the critical external optical and mechanical interfaces coherent to the mission design, e.g. the Mirror S/C frame work structure and the Detector S/C. The technology program is based on the heritage achieved within the context of the XMM/Newton telescope development. The investigations of the correlated programmatic aspects towards the FM production by application of effective robot system supported assembly procedures shall be illustrated.