## 2 Materials and Methods
### 3 DP-WHO Design Process  
For this study, two AM processes, MEX--material extrusion (Enter 3 Pro 3D printer (Shenzhen Creality 3D Technology Co., Ltd., Shenzhen, China) and polylactic acid--PLA) and vat photopolymerization (AnyCubic DLP 3D printer (ANYCUBIC Technology Co., Ltd., Shenzhen, China) and 405 nm basic resin) were used to produce WHO samples (Table 1). Orthoses were designed based on the 3D scanning data of two healthy users acquired with an Artec Eva 3D scanner (Artec Europe S.a r.l, Senningerberg, Luxembourg). The scan's 3D data were processed and exported as STL files using Artec Studio (Artec Europe S.a r.l, Artec 3D, Senningerberg, Luxembourg). The 3 DP-WHOs included Voronoi patterns generated using Meshmixer software (Autodesk Inc., San Francisco, CA, USA) as well as elliptical, tear-shaped, and hexagonal open pockets modeled using CATIA V5 (Dassault Systemes, Velizy-Villacoublay, France) with the goal of addressing a wider range of design and printability related aspects. The lengths of the wrist-hand orthoses were 164 mm and 175 mm, respectively, with a thickness of 2.7 mm for samples 1-8 and 3.7 mm for samples 9-10. Three of the orthosis models were also generated using the flat and thermoformed approach described in [13] for enabling a comparison of their printing time and surface quality with those of orthoses produced directly in their ready-to-use form (based on 3D scans). Thermoforming on the user's hand was performed using the method investigated by [PERSON], et al. [22], which involved immersing the flat orthoses in hot water at 60 \({}^{\circ}\)C to exceed the glass transition temperature of PLA and to render the material malleable. After shaking off the hot water droplets to prevent burns to the user's forearm, the orthosis \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Sample** & **Design** & **3D Printing Process** & **Approach** & **Material** \\ \hline
1 & Tear-like open pockets & MEX & Flat + thermoformed & PLA \\
2 & Tear-like open pockets & MEX & Ready-to-use & PLA \\
3 & Elliptical open pockets & MEX & Ready-to-use & PLA \\
4 & Elliptical open pockets & MEX & Flat + thermoformed & PLA \\
5 & Elliptical open pockets & DLP & Ready-to-use & Basic resin \\
6 & Hexagonal open pockets & MEX & Flat + thermoformed & PLA \\
7 & Hexagonal open pockets & MEX & Ready-to-use & PLA \\
8 & Voronoi 2.7 mm thickness & DLP & Ready-to-use & Basic resin \\
9 & Voronoi 3.7 mm thickness & DLP & Ready-to-use & Basic resin \\
10 & Voronoi 3.7 mm thickness & MEX & Ready-to-use & PLA \\ \hline \hline \end{tabular}
\end{table} 
Table 1: 3 DP-WHOs used in the research. Figure 1: Research approach. was molded to fit the shape of the hand. When cooled down, the orthoses retained their molded shape. Three Velcro straps were subsequently positioned on the palm, wrist, and forearm areas to secure the orthosis on the hand. Figure 2 shows the digital versions of the orthoses processed in Meshmixer for Voronoi pattern generation (Figure 2a) and those modeled in CATIA V5 starting from 3D scans (Figure 2b). The Voronoi pattern was created by reducing the mesh size of the orthosis to control polygon dimensions using the 'Make Pattern' option (Mesh + Delaunay Dual Edges) for pattern generation and setting the size and spacing between elements. To ensure that the orthoses are robust for daily use, the density of the patterns can be adjusted in specific areas using Meshmixer's 'Sculpt \(\rightarrow\) Brushes \(\rightarrow\) Reduce' and 'Sculpt \(\rightarrow\) Brushes \(\rightarrow\) Refine' options. Figure 3 illustrates the development process for the ready-to-use orthoses, which includes STL hand model importation, mesh cleaning and smoothing, orthosis surface generation, 3D modelling of the orthosis by including open pockets, and 3D printing (by DLP, in this example). Figure 3: Three-dimensional scanning-based development pipelines for 3 DP-WHOs.