The fabrication of microstructured workpieces with conventional manufacturing methods, such as turning, milling, shaping or drilling--imposes high demands on the machine behavior and the tool properties. The requirements in terms of machine characteristics are currently met by only few machine tools. An ultra precision milling machine which permits microstructures to be manufactured with optical quality has been designed and built at the IPT in Aachen. Using natural diamond cutting tools, a broad range of materials like, for example non-ferrous metals or plastics, can be machined, producing real 3D-structures with a surface roughness of below 5 nm Ra. Only the diamond can be sharped to the required level of accuracy. Cutting edge sharpness and rounded are crucial to the manufacturing quality of the work piece. Minimum structure sizes in the submicron range and aspect ratios of more than hundred have been achieved by diamond matching at the IPT. Even small series or prototypes can be manufactured flexible and cost- effectively when mechanical cutting techniques are applied. Parts can be mass-produced cheaply when reproduction techniques, such as galvanic forming, injection molding or stamping are applied.