Raptor Prosthetic Hand: Design and Development of a Low-Cost Mechanical Upper Limb

Abstract

This study presents the design and testing of a low-cost, 3D-printed prosthetic hand based on the Raptor Hand model developed by the e-NABLE community. The goal was to create a functional upper-limb prosthesis using accessible materials and fabrication methods. We utilized CAD software to adapt the open-source Raptor design for a pediatric user, printed the components on an FDM 3D printer using PLA filament, and assembled them with conventional cables and springs to enable movement by wrist flexion. The hand's performance was evaluated through simple tasks and mechanical tests, measuring finger range-of-motion and grip strength. Results showed that the prototype achieved approximately 90° finger closure and demonstrated a grip force on the order of 10–15 N, which is comparable to values reported for similar 3D-printed designs. These results, while below those of high-end commercial prostheses, were sufficient for basic gripping tasks. Notable observations included slight loosening of elastic components after repeated use, echoing issues noted in the literature (Cuellar et al., 2021). Overall, the study confirms the viability of a community-driven prosthetic solution: the printed Raptor Hand can perform basic functions effectively, offering a promising low-cost option. This work highlights the importance of material selection and design refinements for future improvements of open-source prostheses.