## 2 Materials and Methods
### 3D Printing Process  
Before 3D printing any object, including WHOs, the operators typically analyze different build orientations and process parameter settings using slicing software. In this research, the Cura Ultimaker slicer for the MEX process and the Chitubox Basic slicer for the DLP process were employed. This step helps in evaluating aspects like volume and position of support structures, filament consumption, printing time, and surface quality (Figure 4). Given the complexity of 3 DP-WHO designs, this study explored not only the common vertical (upstanding) and horizontal orientations (Figure 4a), but also optimized orientations recommended by Meshmixer software (Figure 4b), the Auto-Orientation Cura 5.2.2 add-on (Figure 4c), and build orientation for the part to fit the 3D printer workspace (Figure 4d). The printing speed and temperatures for the extrusion and platform were set based on the type of material and past experience to produce good quality prints.  
The mechanical resistance of 3 DP-WHOs in response to wrist joint movements (flexion/extension, ulnar/radial) depends not only on the values of process parameters but also on the chosen build orientation [13]. At the same time, process parameters such as infill density, layer thickness, and the number of perimeters also influence the production efficiency aspects mentioned earlier.  
Table 2 presents the factors examined for each process along with the printing parameters used to assess their influence on both printing time and surface quality. Initially, these investigations were conducted based on the information provided by slicers. Subsequently, seven orthosis configurations were chosen for manufacturing, and their usability was evaluated (samples 3-9), with the findings discussed in Section 3.  
Figure 5 presents two of the samples during the manufacturing stage: one created through a DLP process (sample 5), and the other 3D-printed in a flat shape (sample 1) intended for subsequent thermoforming on the patient's hand. Several other manufactured orthoses are shown in Figure 6.  
Figure 4: Examples of WHO ready-to-use orthoses oriented differently in Cura and Chitubox Basic: (**a**) horizontal orientation; (**b**) optimal orientation generated by Meshmixer; (**c**) optimal orientation generated by Cura slicer; (**d**) optimal orientation in Chitubox slicer for orthosis to fit the 3D printer workspace.  
Figure 5: Manufacturing of samples 5 and 1: DLP process (**a**), MEX process (**b**).  
\begin{table}
\begin{tabular}{c c l} \hline \hline
**Factors** & \multicolumn{1}{c}{**Levels**} \\ \hline  & _Varied parameters_ & _Fixed parameters_ \\  & & Printing speed: 55 mm/s \\  & & Printing temperature: 210 \({}^{\circ}\)C \\  & & Build plate temperature: 60 \({}^{\circ}\)C \\  & & Line width: 0.4 mm \\ Process parameters (orthoses produced by a MEX process) & \
\begin{tabular}{l} Build orientation: vertical, horizontal, optimized \\ Infill density: 100\%; 80\%; 60\% \\ Infill pattern: lines; zig-zag; grid; triangles \\ Layer thickness: 0.1 mm; 0.2 mm \\ \end{tabular} &
\begin{tabular}{l} Line width: 0.4 mm \\ Wall line count: 2 \\ Top/bottom layers: 2 \\ Build plate adhesion: Brim \\ Support density: 5\% \\ Support pattern: zig-zag \\ Material: PLA \\ Support overhang angle: 63\({}^{\circ}\) \\ \end{tabular} \\ \hline  & & Exposure time: 3 s \\  & & Lift distance: 5 mm \\  & & Lift speed: 2000 mm/min \\ Process parameters for orthoses produced by a DLP process) & Layer height: 0.1 mm; 0.2 mm \\ Wall thickness: 1.2 mm; 1 mm & Return space: 2500 mm/min \\ Infill density: 100\% & Infill structure: Grid3D \\ Material: Basic resin \\ \hline \hline \end{tabular}
\end{table}
Table 2: Three-dimensional printing process parameters.  
Figure 6: Three-dimensional-printed WHOs: sample 3 with Velcro strips (**a**); samples 5–9 (**b**).