The presence of oxygen in the PBF-LB/M process leads to embrittlement in the workpiece in materials with high affinity to oxygen. Especially the metal powder Ti-6Al-4V requires a special protective atmosphere during processing. By doping the argon 1.5 \% with monosilane, the residual oxygen of a usual argon atmosphere is bound and reduced to a value typical for XHV (Extreme High Vacuum). Basically, the development of an PBF-LB/M system according to VDI 2221 is presented. The admixture of silane requires an innovative machine concept in order to ensure the compatibility of the materials used and to prevent the process gases from becoming hazardous. The phases of development are accompanied by comprehensive reaction studies and flow simulations. The resulting concept relies on a compact machining area (Ø100x100mm) and breaks new ground in the processing of special materials, not only through the process gases used, but also in powder and workpiece management.