Upper- and lower-limb orthotic devices are prescribed for individuals who have partially lost motor control, such as stroke survivors or those with cerebral palsy, to assist with the stability and function of a limb. Unlike prostheses, devices available for those missing part of a limb, there are few current solutions available for upper-limb orthoses. As a result, options for users can be clunky, expensive, and hard to customize. The goal of this research was to further develop a 3D-printed elbow-driven orthosis that is inexpensive, adjustable, and helps users with impaired dexterity perform two-handed daily tasks. In comparison to traditional devices, which can cost hundreds of dollars, this orthosis can be assembled for approximately $30 predominantly because of the use of 3D printed parts. Originally designed for an individual whose seizure reducing brain surgery limited use of her left hand, this orthosis takes advantage of existing elbow range of motion to operate a clamp near the user’s palm by using a cable extending from the elbow to the hand. Cable tension activates the clamp near the palm in two distinct ways, depending on chosen part placements; the cable can either voluntarily open the clamp, or voluntarily close the clamp with elbow flexion. To compare clamp activation methods, we conducted a study that evaluated muscle activity and time to complete activities of daily living using the adjustable orthosis. These results will help inform which device setting, voluntary opening or voluntary closing, is easiest to control for common tasks and inform future device improvements. Participants involved in this study included individuals with impaired and unimpaired hand function. Through a continuous cycle of prototyping, feedback, and device modifications, we have created a customizable, affordable, 3D printed upper-limb orthosis that will be open-sourced to promote further innovation to support individuals with limited hand function.