## 2 Materials and Methods  
The methodology used in the present investigation is depicted in Figure 1. More particularly, Figure 1a illustrates the stages of the method used for the specimens' preparation, assessment, and characterization, as well as the evaluation of the experimental results of the present study. Pictures from the trial-based course are shown in Figure 1b. In particular, Figure 1b shows: how the raw material was dried (PA6 Novamid N X 160 pellets acquired from DSM Engineering Materials at 60 \({}^{\circ}\)C for 24 h) in subfigure no 1, the extrusion of filament using a 3 devo precision single screw extruder from the Netherlands' Utrecht (filament's diameter 1.75 mm, first and fourth heat zones: 190 \({}^{\circ}\)C, second and third heat zones: 220 \({}^{\circ}\)C, 3.50 rpm, fan: 80.0%) in subfigure no 2, the drying process of the created filament (4 h at 60 \({}^{\circ}\)C) in subfigure no 3, and 3D printing of the samples in agreement with ASTM D695-02a standard (five replicas for each set of 3D printing settings, using an Intamsys 3D printer, Funmat HT, from Shanghai, China) in subfigure no 4. The 3D printing procedure's parameters are displayed in Figure 2. The energy assessments conducted during the 3D printing procedure employing a digital multimeter Rigol DM-3058E (RIGOL Technologies, Shanghai, China) are presented in subfigure no 5 of Figure 1, the examination of the specimens' morphology using an optical microscope (Kern OKO-1, Germany; 5-MP type with ODC-832 camera) in subfigure no 6 of Figure 1, and the evaluation of the specimens' compressive strength (Instron KN-1200 universal testing machine, from Norwood, Massachusetts, USA) in subfigure no 7 of Figure 1. The robust design algorithm implemented in this study for the optimization and evaluation of the experimental findings is shown in Figure 1c. Therogravimetric Analysis (TGA) (Perkin Elmer Diamond, 30-550 \({}^{\circ}\)C heating course with a 10 \({}^{\circ}\)C/min step) and Differential Scanning Calorimetry (DSC) (TA Instruments DSC 25 apparatus, 25-220--25 \({}^{\circ}\)C heating cycle, 15 \({}^{\circ}\)C/min step) were used to assess the specific PA6 material's thermal sensitivity, and the relevant graphs are shown in Figure 2a,b, correspondingly. This investigation aimed to examine the thermal sensitivity of the particular PA6 material to make sure that the temperatures utilized to produce filament through melt-extrusion and the extrusion process in the 3D printer do not affect the thermal stability of the material or result in material degradation. The TGA measurements (Figure 2a) show that the Bed Temperature (BT) and the Nozzle Temperature (NT) used in the study for the 3D printing of the samples are lower than the temperature at which the PA6 starts to degrade. So, no such phenomena are expected to affect the performance of the 3D-printed samples. Additionally, the DSC curve (Figure 2b) shows that the temperatures used are in a range where the PA6 is not changing phase. The three primary components of the overall electric energy consumption during the MEX-AM course are (i) consumption at machine startup, (ii) consumption throughout the manufacturing 3D printing stage, and (iii) consumption after the manufacturing process, until the machine shutdown. The following equations are used to calculate total energy consumption [18]:  
\[E_{total}=E_{thermal}+E_{motion}+E_{auxiliary} \tag{1}\]  
Figure 1: Work procedure: (**a**) methodology steps of the experiments; (**b**) experimental procedure highlights; (**c**) robust design algorithm. Figure 2: Values for 3D printing parameters and the compression test sample’s geometry made in accordance with ASTM D695 specifications are shown. The right side of the figure shows (**a**) a TGA graph of the weight loss versus temperature for the particular PA6 utilized in the study and (**b**) a DSC graph.