Product engineering of micro and nano technology (MNT) devices differs substantially from product engineering in more traditional industries. The general approach is mostly bottom up, as it centers around the available fabrication techniques. The strong emphasis on manufacturing technology in this area leads to a large number of application specific fabrication processes. In the first part of this paper we introduce a comprehensive customer-oriented product engineering methodology for MNT products. The MNT product engineering process is analyzed for different business cases with regard to application-specific procedures and (data) interfaces. An existing environment for the development of MNT manufacturing processes has been identified as a technical foundation for the methodology and will be described in the second part of this paper.