## 3 Results and Discussion
### Additive Manufacturing Results
There was complete contact between the surface and the unit cell because a periodic cellular structure was implemented; incomplete unit cells can be observed and, in the perimeter of the insole, there was an accumulation of material in the struts of the BCC cellular structure. Employing FFF usually leaves burrs and barbs on the surfaces [40]. Figure 15 shows that the most affected surface areas presented as low quality as more irregularities in the design (toes and forefoot) can be observed, causing unwanted surface traces in the insole. 3. The feasibility to adapt two cellular structures (BCC and TPMS) to the interior of the insoles was demonstrated; these insoles presented a higher displacement of their upper surface than the solid insoles due to the spaces generated between the unit cells of the cellular structure. The insole design that incorporated the BCC cellular structure had a lower displacement of its surface than the TPMS because the geometry of the unit cells prevented a higher displacement. It was observed that the displacement of the top surface of the insoles depends on the geometry of the unit cell and not on the rigidity of the cellular structure. 4. The stiffness of the cellular structures was characterized via FEM, and the TPMS cell structure was stiffer than the BCC; however, the insoles that integrated the BCC cellular structure presented lower displacement due to the geometry of the cellular structure. 5. Using cellular materials in the model could help enhance the performance of the insoles towards more personalized products. Different cellular topologies could be beneficial for different performance demands and results. Specifics of the intended use should be considered in order to select the cellular topology. 6. Defects, such as the star-case effect obtained on the upper sections of the insoles could be reduced with the use of curved-layered FFF. This method has shown to be efficient for this purpose, while enhancing the mechanical properties of the fabricated part. This is achieved by ensuring raster continuity that conforms precisely to the targeted surface. 7. The results of the static simulation showed that the topologies and models proposed here showed promising performances. However, insoles could also be exposed to high frequency loading scenarios (especially for sport users). Therefore, future research should focus on understanding and characterizing the dynamic response to such structures. For dynamic loading scenarios, surface-based structures have shown better performance as they reduce stress concentrators [10; 41]. 8. Concerning the development of personalized products, functionally graded structures offer a solution to very specific desired responses. Preliminary tests and scans showed areas with higher pressure concentrations; depending on the desired performance, these could be filled with specific topologies or volume fractions, while, in other less demanding regions, alternatives could be explored. With the methodology used in this work, the fabrication of a functional insole was achieved, and the use of technologies (3D scanning and AM) can help to reduce the manufacturing time and costs of the insole, being a viable alternative for its fabrication. This work presented a preliminary study on the validation of the computational design in static conditions using FEM. Therefore, to complement the validation of the design and manufacturing of the insole, future work should characterize the properties under dynamic loading conditions of the 3D printed insoles. This will allow the evaluation of their performance under loading conditions produced in the gait cycle while considering the possible printing defects inherent to the FFF process. Conceptualization, G.R.-B. and E.C.-U. ; methodology, G.R.-B. ; formal analysis, G.R.-B. and E.C.-U. ; investigation, G.R.-B. and E.C.-U. ; resources, K.A.C.-G. and L.A.M.-H.; data curation, L.A.M.-H.; writing--original draft preparation, G.R.-B. ; writing--review and editing, E.C.-U., G.I.P.-S. and K.A.C.-G.; visualization, G.R.-B.