The majority of arm amputees live in developing countries and cannot afford prostheses beyond cosmetic hands with simple grippers. Customized hand prostheses with high performance are too expensive for the average arm amputee. Currently, commercially available hand prostheses use costly and heavy DC motors for actuation. This paper presents an inexpensive hand prosthesis, which uses a 3D printable design to reduce the cost of customizable parts and novel electro-thermal actuator based on nylon 6-6 polymer muscles. The prosthetic hand was tested and found to be able to grasp a variety of shapes 100% of the time tested (sphere, cylinder, cube, and card) and other commonly used tools. Grip times for each object were repeatable with small standard deviations. With a low estimated material cost of $170 for actuation, this prosthesis could have a potential to be used for low-cost and high-performance system.