I created CAD of a complete prototype in SolidWorks, including mechanical mates. The virtual four bar mechanism enables rotation beyond 180 degrees, so the gripper can be compact and secure when not in use, while not requiring additional actuators. The design also includes a worm gear to prevent back driving from the grasped object that would require continuous force application. For potential integration into a larger mechanism, the wrist of the mechanism fits standard box tube, and a motor would be positioned within the robotic arm.

In order to fabricate this prototype, I utilized the devices and materials I had available. The virtual four bar mechanism uses wire in catches, and all other components are 3D printed. I restored and calibrated a decade old unsupported 3D printer for this purpose, including manually reflashing the Marlin firmware version for updated G-code commands. Here is a video of me trying out the gripper for the first time after it was completed:

In the next iteration of this design, I plan to fabricate the structural components from bent sheet metal, and use commercial-off-the-shelf components for the gears, axles, and timing belts. While the wires did work in this prototype, replacing them with timing belts will contribute to ease of assembly and a simpler interfacing part.