## 3 Results
### Warehouse Process Analysis and User Story Identification  
The mapping of Focchi S.p.A.'s ETO warehouse processes was conducted using the user-centered design methodology to identify the key stages of the activities of the warehouse, user groups, and explicit their needs through user stories. This approach facilitated the definition of the process of ETO and the definition of user requirements, and their subsequent translation into technical requirements, aligning with the research objectives. User stories were further utilized to collaboratively establish Key Performance Indicators (KPIs) with warehouse personnel through individual interviews, ensuring a user-centric validation process. Table 1 reports the process within the use case of Focchi S.p.A. but considers a reference of a similar ETO model for customized prefabricated building products. The manufacturing and warehousing processes in an ETO company project involve multiple stages with various stakeholders participating within a flow which supports the identification of users and information to be managed and organized. The process goes from the reception to the management of materials, components, and stillages within the warehouse to the end-product management before shipment. The stages report these activities, and they are used as a reference for a further data-driven approach in DT design. The table summarizes the stages, the tasks, and the users involved. Based on this process analysis, the users are identified for further workshops and interviews. Eighteen employees, representing both Office (O) personnel (n = 6) involved in warehouse operations and Warehouse (W) operators (n = 12) are engaged in logistical and production line supply activities. These diverse groups provided valuable insights into the current challenges and desired improvements. Analysis of these stories, excluding those beyond the scope of DT implementation, revealed key pain points and areas for improvement. A comprehensive list of user stories and their associated outcomes is available in Appendix A. These findings informed the preliminary definition of technical specifications and business intelligence KPIs to be incorporated into the digital twin. Through a series of workshops and interviews, the process was defined and a diverse set of user stories was compiled. Figure 2: Outdoor warehouse in Focchi S.p.A. The ETO model requires a warehouse with a high variability and low replicability of materials and components. These stories encapsulated the specific needs and expectations of different stakeholders. The user stories highlighted the need for a solution, deployable in a digital twin, that could provide real-time data, improve communication, and automate tasks with functionalities which can be summarized in the following needs:  
* Enhanced materials, components, and stillages visibility and tracking:
* Real-time visibility of vehicle traffic, warehouse access points, inventory levels, package locations, and personnel/vehicle locations. * Unique identification and tracking of materials, components, and stillages. * Improved Efficiency and Optimization:
* Optimized route suggestions for material transport. * Efficient packages search functionality. * Streamlined check-in process and optimized storage locations. * Faster and more productive work through better task assignments and organization. * Real-time task status updates and efficient task allocation. * Optimized warehouse layout and clear traffic routes. * Real-time updates on production schedules and task prioritization. * Enhanced Safety:
* Real-time location tracking of personnel and vehicles for collision prevention. * Improved visibility for pedestrians and bikers in warehouse areas. * Communication and Collaboration:
* Real-time communication platform for information sharing and collaboration. * Clear communication of schedules and priorities. * Resource (personnel and space) Management:
* More available storage space for prepared materials and components.