## 3 Methodology and Guidelines
### In-Depth Analysis  
After the Potential Analysis, a preliminary design solution is required. In fact, deeper assessments on the manufacturability by AM and its convenience against other production systems follow a conceptual design of the product itself, at least at a sufficient level of geometrical detail. Generally speaking, the conceptualization phase is highly onerous in terms of time and work and impacts on the design department. So, before developing a conceptual design, it is advisable to discard unpromising ideas following the steps described above, thus focusing efforts only on the most attractive candidates. Therefore, the In-depth Analysis stage has been conceived to include the following evaluations (Figure 5):  
1. Develop a conceptual design and its preliminary geometry;
2. Evaluate the geometry according to three indices: Customization Index, Complexity Index, Printability Index;
3. If necessary, refine the geometry or change the intended orientation of the part in the printer;
4. Accurately evaluate the manufacturing process on the selected printer by suitable numeric tools. The conceived geometry, either by direct CAD modelling or TO tools, is then evaluated according to three indices that are strictly related to the designed shapes:  
1. Customization Index: the term customization means the product development according to individual/personal specifications or preference. This index refers to the level of customization that the product must comply to satisfy the customer's requirements, ranging from no customized products to truly unique parts [38; 39].
2. Complexity Index: it assesses the complexity of geometries in relation to the difficulty of achieving the shape with AM competing techniques. For instance, in [40], the authors have developed such an index to calculate the shape complexity of cast parts.
3. Printability Index: it is composed of indices related to the limits of AM in obtaining certain geometric features [41]. For example, excessively bulk geometries can lead to distortions; too thin walls and too small holes are difficult to produce; cantilevered surfaces require supports which must then be removed. In Table 6, indices to be considered are summarized. The weights to balance the indices should be assigned accordingly to the specific needs and application context. Indeed, the Printability Index is closely related to the part orientation in the printer.  
The first two indices are used to estimate the level of customization and complexity of the geometry according to standard technologies. The Printability Index aims to highlight the criticalities in the conceived design according to the main DFAM guidelines and common geometric limits of AM. Such an index allows the designer to identify changes in the geometry as well as more convenient orientations of the part.  
At this stage, numeric simulations are required to verify the stress level in the part according to operating conditions and the peculiar characteristics of the metalluric mi crostructure or the anisotropy induced by the layered deposition. Moreover, the thermal gradients usually arising in the process lead to residual stress, which must be carefully assessed with dedicated software tools which are consolidating in the market.  
This process leads to a detailed and definitive geometry which allows more precise evaluations on the printing process. Parts nesting can be computed, and selected machine volume optimally occupied. Indeed, if more printers are available and compatible with the chosen material and part size, the optimal one can be selected by iteratively simulating the printing process and expected parts quality against the fixed requirements.  
Ultimately, if there is at least one printer compatible with the production requirements, it is possible to move on to the last step of the workflow.