## 4 Fabrication and Validation  
The solution of the optimized design was selected for physical prototyping by using an EOS M400. In Figure 15a the component after the exceeding powder removal and before the detachment from the building platform is shown. The cutting and the support structure removal were provided with care and a manual assembly made use of the jig as reported in Figure 15b. This configuration was used as a fixturing system for the machining of the additional material (Figure 15c). The most time-consuming operation is the PBF-LB/M fabrication as evidenced in Table 7. The AM step requires 53% of the total time. Particular care was paid to the CNC removal of the additional material which took 44 h accounting for 28% of the total time. Additionally, it is relevant to note that the AM fabrication is automatic after setting up the system, hence it required 4 days as well as the CNC machining that was undertaken during a normal working shift. The traditional machining of the original design is also reported for comparison. The aluminum solid stock is firstly cut by wire EDM and a stress-relieving heat treatment follows. The CNC strategy is roughing, rocketing for the inside of each area surrounded by the ribs, and finishing. As expected, a very long time is required for pocketing and finishing since the forces must be kept very low for avoiding deformations of the thin walls [64]. These long processing times highlight that the satellite  
Figure 14: Investigated lattice structure modal analysis results versus panel weight. Figure 15: Fabricated component (**a**), assembly within the jig (**b**), machining (**c**). structure is expensive if compared with serial production via traditional technology. It is noteworthy that the structure, in this case, is simplified to allow the tool accessibility and functionality can be reduced or compromised as in the present case where the natural frequency specification was not accomplished. When complex and low-mass parts are produced, the AM becomes competitive and can enable the possibility to fabricate high-performance structures allowing relevant cost-saving in space missions at different levels. The machined component was subjected to tolerance verification. In Figure 16 the dimensions and required tolerances are shown. The measured ones are indicated in green. Table 8 reports the outcomes of the analysis. The total wall thickness is within the requested range and shows only positive deviations, hence, a slightly bigger weight than the designed one is expected. The distances between the junction points vary within a few hundred mm, widely meeting the requested \(\pm\)0.25 mm. Analogously, all the measures are taken on the component height range within \(\pm\)0.05 mm. An important role is played by the junction point mating pit and tooth shown in section S-S in Figure 16. Additionally, for these features the required limits are satisfied demonstrating the possibility to use the manufacturing coupling between AM and CNC to provide an in-tolerance satellite structure. A microstructural analysis was performed on the fabricated component. Surfaces were cut by Struers(r) Labotom 6, polished by a Struers(r) Labopol and etched with Weck's reagent. The vertical wall shows a typical microstructure evidencing the contour and hatching laser strategies (Figure 17a) [55]. Partially superimposed melt pools are well evident as typical for this AM technology. A little defect can be noticed in the contour zone: the rounded shape can suggest it depends upon a trapped gas, probably due to some inefficiencies of the protective flow [65; 66]. Indeed, big machines such as the EOS M400 suffer from uniform gas distribution which may affect the powder bed development of this light alloy. Figure 17b shows the section on the lattice structure: the contour and hatch zone can be identified; also in this case, a small defect is present. The examination at higher magnification (Figure 17c) highlights that the cellular structure grows in the direction of the co