This paper presents the design and construction of a low-cost, Arduino Nano-based myoelectric prosthetic arm to increase access to assistive technology to underprivileged populations. The system leverages surface electromyography (sEMG) signals recorded from non- invasive Ag/AgCl electrodes to signal voluntary muscle contraction. The signals are interpreted by a simple threshold-based control algorithm, eschewing the use of advanced machine learning in favor of reliable and responsive performance. Upon exceeding a calibrated threshold, servo motors built into a 3D-printed PLA arm are actuated to mimic simple hand movements like opening and closing. The use of open-source hardware, low-cost materials, and additive manufacturing processes like FDM 3D printing guarantees a low-cost manufacturing process, permitting simple assembly, repair, and modification. The prosthesis is energy efficient, modular, and lightweight, ideal for educational use, rural hospitals, and prototyping. Experimental testing confirms consistent performance and real-time responsiveness to muscle activity. In summary, this paper demonstrates a low-cost, accessible, and scalable approach to functional prosthetic limb design, closing the gap between advanced biomedical solutions and those communities in need of them.