Amputees face significant challenges in performing daily activities after losing an upper limb. Replacing a lost limb with a device with capabilities comparable to a human hand is a keen area of interest for prosthetics researchers. Despite advances in the field of prosthetics, the number of amputees who use these devices remains low. This study presents an open-source, low-cost, and anthropomorphic prosthetic hand solution for people with upper-limb amputations that outperforms currently available devices in terms of usability and biomimetic performance. The work aims to improve the acceptance of these devices among amputees by reducing the cost and improving the performance of these devices. We briefly discussed how the adaptive force magnification technique could be applied to a prosthetic device to improve biomimetic performance characteristics such as gripping force and velocity. A non-backdriveable modular under-actuated mechanism is designed that synergistically moves the fingers to adapt according to the shape of the object. The developed device costs one order less than the cheapest available prosthetics in the market and is customizable according to the user. The experiments were conducted to evaluate the biomimetic performance characteristics and the grasping effectiveness of the device in performing activities of daily life.