## 6 Conclusions and Further Work  
This work had the primary goal to systematically provide a solid groundwork based on use cases in order to establish a reference process for the development of iMMS. For this purpose, needs, critical points and existing approaches were identified, and a new approach was presented. Before that, the relevance of the work was shown, and definitions of the terms \"mass customization\" and \"individualization\" were collected. Subsequently, a new definition of the term iMMS was created. Due to the technology dependency of MMS, a technological framework for the manufacturing of iMMS was also established in Section 1 through previous work and a detailed literature review. These are MID technologies in combination with DMT. Based on these technologies, use cases for iMMS were created and collected through expert interviews. After creating a repertoire of use cases, a novel methodology to abstract use cases in product groups was developed that is based on qualitative content analysis. Then, the requirements for each use case were defined and evaluated with the experts. The abstraction of the use cases was an easement for defining requirements. Consequently, product groups were formed for the respective use cases, which have both the most important development activities gained through the qualitative content analysis and weighted requirements. Thus, the novel methodology allows a qualitative assignment of properties and characteristics to product groups with their weighted requirements. Finally, a real case study was conducted to analyze and confirm the manufacturability with MID technologies and DMT and to find suitable reference processes that can be later tailored to iMMS. Furthermore, the case study revealed weaknesses and gaps within the design process for iMMS. This case study also shows the integration of automated slides into soft tooling that is fabricated from the same material as the soft tooling and operated by the clamping forces of the injection-molding machine. This production process is also a novelty [29] and has not been investigated in the context of EDP. It is especially the necessary correction loops that have to be executed due to the individuality of the products, which is the main challenge in the development of iMMS. On top of that, digital technologies, such as additive manufacturing, must be used for the production of individualized products. Such technologies are new. Hence, very few empirical values are available. With the gained insights from this work, new research questions can be derived. One of these could be: Which product development methods can help reduce correction loops within the development and manufacturing of iMMS? This enables creating a novel EDP with the supported methods. Nonetheless, the defined requirements can expand and change as more use cases are collected. In the context of this work, it also became clear that valuable knowledge was gained through real case studies. A recommendation to identify further critical points of the design processes for iMMS is to implement and observe further real case studies.  
Conceptualization, F.C.; methodology, F.C.; validation, F.C. and K.-P.F. and A.Z.; formal analysis, F.C.; investigation, F.C.; resources, F.C.; data curation, F.C.; writing--original draft preparation, F.C.; writing--review and editing, F.C., K.-P.F. and A.Z.; visualization, F.C.; supervision, K.-P.F. and A.Z.; project administration, F.C.; funding acquisition, A.Z. All authors have read and agreed to the published version of the manuscript.  
Baden-Wurttemberg's Ministry of Economic Affairs, Labour and Housing, Grant Number 213234 funded this research.  
Not applicable.  
The authors declare no conflict of interest.