## 3 Results
### Manufacturing and Assembly Results  
All the parts were manufactured successfully at first attempt. As expected, the printing time was about 21 h for the socket and about 33 h for the other elements, with the material consumption also being generally compatible with the initial estimation. The obtained model required additional post-processing consisting of removal of the supports produced during printing. All the parts were manufactured in a stable manner, without any large errors or deformations. Minor problems occurred at one end of the forearm (contact surface with the socket part), and it was slightly deformed and needed some manual post-processing for better fitting and strength.  
The assembly process started with putting together mechanical parts of the prosthesis, starting from the end effector (modified C-shape), with a simplified wrist joint connecting it to the forearm part. The assembled module is presented in Figure 24.  
The second step was putting together the electronic system and placing it inside cavities of the forearm. At this step, some adjustments were made to assure better fitting and access to the mounting elements, so that disassembly of mechanical components of the prosthesis is possible without removing the electronic part (easy access with tools). Also, cable feedthroughs had to be made slightly wider, to accommodate for the cable connections between modules. These efforts are presented in Figure 25.  
In the three cavities in the prosthesis forearm, the electronic components placed were as follows:  
1. The first narrow hole near the wrist was used for SD card reader and output of USB cable for power source (Figure 26a);
2. The second, central hole at the forearm was used as a hosting place for the main microcontroller (Figure 26b);
3. The third, widest opening near the connection to the socket was used to mount the force sensor controller and the IMU device (Figure 26c).  
The assembly required using standard manual and power tools. Also, some electronic connections needed to be reinforced by soldering.  
In the final stage of the assembly, the socket was assembled with the other parts. This was made mechanically, with screws. After joining the parts together, the force sensor was screwed to both the parts. As there were slight discrepancies in mounting hole distances between project and printout, the force sensor had an initial pre-tension, which was then accounted for in the data gathering algorithm. The complete prosthesis is shown in Figure 27.  
Figure 24: Assembled prosthesis forearm and end effector.  
Figure 25: Assembly of electronic components—putting microcontroller in central hole.  
Table 4 contains a summary of working times of the subsequent stages of prosthesis development as assumed for a single patient, excluding the design phase.  
\begin{table}
\begin{tabular}{c c c} \hline \hline
**No.** & **Stage** & **Time Elapsed (h)** \\ \hline
1. & 3D scanning and data processing & 0.5 \\
2. & 3D printing of parts & 54 \\
3. & Post-processing and mechanical assembly & 0.5 \\
4. & Electronic part assembly & 1 \\
5. & Coding and testing & 6 \\
6. & Assembly of electronic and mechanical parts & 1 \\ \hline Total & 63 \\ \hline \hline \end{tabular}
\end{table}
Table 4: Working times of stages of prosthesis development (assumption of single patient case).  
Figure 27: Complete assembly of the mechatronic prosthesis.