## 3 Results
### 3 DP-WHO Cost Analysis  
Three-dimensional printed orthosis costs are also an important factor to analyze. These costs include not only production costs related to the quantity of materials used, energy costs associated with printing time, and the 3D printer amortization (or depreciation) costs, but also the design time. By far, the most significant cost component is the design time, especially for the first approach based on 3D scanning the patient's upper limb, which requires specific engineering skills.  
For example, the flat orthoses were generated using a freely available web app. The costs of orthoses 1, 4, and 6 were calculated based on material/filament consumption (52% of the total cost), energy consumption (24% of the total cost), 3D printer amortization (22% of the total cost), and post-processing (2% of the total cost). For orthosis 1, the material consumption was 42 g (13.92 m of filament), and the printing time was 4 h and 19 min at 80% infill density (Table 3), resulting in a cost of EUR 8.45. In contrast, the production costs  
\begin{table}
\begin{tabular}{c c c} \hline \hline
**Sample** & **Levels** & **3D Printing Time** \\ \hline \multirow{4}{*}{5} & Layer height: 0.1 mm/Wall thickness: 1.2 mm & 3 h 44 min \\  & Layer height: 0.2 mm/Wall thickness: 1.2 mm & 1 h 52 min \\  & Layer height: 0.1 mm/Wall thickness: 1.2 mm & 3 h 43 min \\  & Layer height: 0.1 mm/Wall thickness: 1 mm & 1 h 52 min \\ \hline \multirow{4}{*}{8} & Layer height: 0.1 mm/Wall thickness: 1.2 mm & 3 h 44 min \\  & Layer height: 0.2 mm/Wall thickness: 1.2 mm & 1 h 52 min \\  & Layer height: 0.1 mm/Wall thickness: 1.2 mm & 3 h 44 min \\  & Layer height: 0.1 mm/Wall thickness: 1 mm & 1 h 52 min \\ \hline \multirow{4}{*}{9} & Layer height: 0.1 mm/Wall thickness: 1.2 mm & 3 h 44 min \\  & Layer height: 0.2 mm/Wall thickness: 1.2 mm & 1 h 53 min \\  & Layer height: 0.1 mm/Wall thickness: 1.2 mm & 3 h 44 min \\  & Layer height: 0.1 mm/Wall thickness: 1 mm & 1 h 53 min \\ \hline \multirow{4}{*}{10} & Layer height: 0.1 mm/Wall thickness: 1.2 mm & 4 h 18 min \\  & Layer height: 0.2 mm/Wall thickness: 1.2 mm & 2 h 13 min \\ \cline{1-1}  & Layer height: 0.1 mm/Wall thickness: 1.2 mm & 4 h 18 min \\ \cline{1-1}  & Layer height: 0.1 mm/Wall thickness: 1 mm & 2 h 13 min \\ \hline \hline \end{tabular}
\end{table}
Table 4: Three-dimensional printing time for DLP-manufactured wrist-hand orthoses.  
Figure 12: Sample 5 oriented in a Chitubox Basic slicer (**a**); sample 5 after 3D printing (**b**).  
for a ready-to-use orthosis, such as orthosis 3, are double due to a printing time of 8 h and 49 min at 100% density, a 0.2 mm layer thickness (Table 3), and 26.32 m of filament.  
For DLP, orthosis 5, the cost was EUR 5.23 for 3 h and 43 min of printing time with a layer height of 0.1 mm and wall thickness of 1.2 mm.  
Thus, it can be seen that the production costs are low, which is another benefit of 3D-printed orthoses. This opinion is shared in other studies, such as [23; 24], which addressed 3D-printed orthosis (full cast) costs and concluded that they are half the price of conventional orthoses. The following mean printing time and costs were reported in [23]: 129 min and EUR 187 for 3D-printed orthoses, compared to 269 min and EUR 398 for conventional orthoses. A note should be made here that, in our study, orthoses are not full casts fully encircling the arm, but splint-like.  
Cost-related aspects are also presented by [PERSON] et al. [18], who discuss the influence of three printing strategies (layer, thickness, infill) and four types of filaments on mechanical resistance, printing time, and costs. The reported production costs were below a reference cost of USD 75 (conventional orthosis) with an acceptable printing time corresponding to two shifts (16 h).