## 3 Results and Discussion
### Device Building
To ensure that the device can be properly installed during clinical validation, a Velcro fastening system was developed and will be incorporated in the subsequent phase of the process. Clinical validation will be conducted by the multidisciplinary team at the Bioengineering Laboratory (LABBIO) at UFMG, where this phase will take place. The present study focused solely on the development and engineering analysis of the prosthesis, as described above. This device allows for adaptable gripping movements to hold objects of different shapes and sizes. It is capable of handling items such as a 500 mL PET bottle of water, a Fuji apple with an approximate diameter of 80 mm, a cube with 10 mm edges, cylinders from various screwdrivers, and a whiteboard marker with dimensions of 125 mm in length and 15 mm in width. Additionally, the device supports lifting other objects with varying weights, as long as they do not exceed the maximum limit of 2 kg, ensuring functionality and versatility in daily use. The estimated cost of the hand prosthesis is approximately BRL 300.00 (USD 50.15), representing a low-cost option compared to conventional passive and active mechanical prostheses, which range from BRL 1500.00 (USD 254.74) to BRL 5790.00 (USD 984.26) [21]. In addition, upper limb prostheses with advanced operating systems on the global market can cost between USD 30,000 and USD 65,000 per unit [40; 41]. The cost estimate for the prosthesis developed in this study was based on a detailed analysis of several factors, including the materials used, the manufacturing process, and associated operational costs. The polymer filament used for the 3D printing of the prosthesis was the main cost component, priced at BRL 230.00 (USD 38.50) per kilogram. Considering the total weight of the prosthesis is 240 g, the material cost per unit was calculated at approximately BRL 51.23 (USD 8.60). This value represents a significant portion of the total production cost, as the selected material offers good mechanical strength and lightness, which are essential for the prosthesis's proper performance. In addition to the material costs, the 3D printing process itself is another relevant factor in the cost estimate. The prosthesis was manufactured using Fused Deposition Modeling (FDM), a process that, while efficient and cost-effective, incurs expenses for printer maintenance and energy consumption. The printing time cost was calculated based on energy consumption rates and the number of hours required to produce the prosthesis, resulting in an approximate value of BRL 15.00 (USD 2.55) per unit. Other operational costs include auxiliary tools, such as modeling software, which allowed the prosthesis design to be customized for different amputation levels, and the use of surface finishes to ensure a proper and comfortable finish for the user. These additional costs were estimated at around BRL 15.00 (USD 2.55) per unit. Compared to traditional prosthesis alternatives, the additive manufacturing approach offers a significantly more affordable solution, with the added advantage of being customizable for different amputation types and functional levels. This reduced cost allows the prosthesis to be a viable option for a greater number of users, providing an accessible solution without compromising on quality and mechanical efficiency. The prosthetic device combines lightness, strength, and functionality, being accessible and efficient for rehabilitation. Manufactured in Triton using 3D printing, it offers versatile performance at a reduced cost, standing out as an innovative and affordable alternative for hand prostheses.