## 5 Evolution of Robotic Prostheses with 3D Printing  
The evolution of prosthetics has been marked by constant technological and scientific advances, from simple mechanical extensions to highly functional robotic devices. In this context, the introduction of 3D printing has represented a paradigm shift, allowing for greater customization, cost reduction, and wider access to advanced technologies. To understand the magnitude of this advance, it is important to trace the development of robotic prosthetics from their earliest mechanical designs to modern devices that combine sensors, actuators, and 3D-printed bio-compatible materials [24].  
The development of 3D printing at the end of the twentieth century radically changed the landscape of the manufacture of robotic prostheses. This technology, which allows for the creation of three-dimensional objects by superimposing layers of materials, transformed the design and production processes. The ability to create custom parts accurately and quickly made it easier to adapt robotic prosthetics to the individual needs of users [25].  
The e-NABLE project, launched in 2011, was one of the pioneers in the use of 3D printing to manufacture low-cost prosthetics for children (Figure 4). This project demonstrated that it was possible to produce functional devices at a fraction of the cost of traditional prosthetics, and it ushered in a trend towards democratizing access to customized robotic prosthetics [26].  
\begin{table}
\begin{tabular}{l l l l} \hline \hline
**Name of the Prosthesis** & **Maker** & **Price, USD** & **Features** \\ \hline Hero Arm [15] & Open Bionics & 3000–5000 & Lightweight, multi-grip prosthesis, compatible with children and adults, customized, bionic design \\ LUKE Arm [17] & Mobius Bionics & 100,000 & Advanced, multi-articulated prosthesis, electrode \\  & & & control, high precision and functionality \\ i-Limb Quantum [18] & Ossur & 80,000–100,000 & Intuitive control, various grip patterns, water resistance, quick grip change \\ MyoPro [19] & Myomo & 25,000–50,000 & Arm support system, electromyographic control, movement assistant \\ Michelangelo Hand [20] & Ottobock & 60,000–75,000 & Natural look, multiple grip modes, intuitive control, rotating wrist \\ bebionic Hand & Ottobock & 40,000–60,000 & High functionality, aesthetic design, multi-grip, durable materials \\ TASKA Hand [21] & TASKA Prosthetics & 50,000–60,000 & Waterproof, multi-grip, robust and durable \\ TrueLimb & Unlimited Tomorrow & 7995 & Custom design, 3D scanning for fit, multiple color and design options \\ Nexobrace [22] & YouBionic & 1200 & Muscle control, 3D printing, customized, simple design \\ Handiii [23] & Exiii & 300–500 & Low cost, smartphone control, 3D printing, light weight \\ \hline \hline \end{tabular}
\end{table}
Table 2: Commercial prosthesis price list.  
Figure 4: Low-cost prosthetics for children designed by e-NABLE project [27].  
The evolution of robotic prostheses with 3D printing has allowed for the creation of devices that not only fulfill the basic functions of a prosthesis (such as replacing a lost limb), but can also incorporate advanced features such as pressure sensors, myoelectric control, and actuators that replicate complex movements. This has been made possible by the use of computer-aided design (CAD) software, which allows engineers to create highly accurate three-dimensional models that can then be printed with various materials, from plastics to light metals (Figure 5).  
Three-dimensional-printed robotic prostheses have evolved at a fairly rapid pace, so Table 3 provides a summary of some of the most important events in this area. Table 3 is not a complete summary; it only shows specific events that were part of the development process of prostheses with the intervention of 3D printing.