Tensegrity robots have future applications in search and rescue, where they could stack on top of one another to form bridges across unstructured terrains. The name tensegrity is a portmanteau of “tensional” and “integrity”, meaning that these kinds of robots have rigid components in compression and elastic components in tension. Our project at the Faboratory, titled Variable Stiffness Tendons (VST), uses principles in soft robotics to design and characterize a compliant mechanical tendon that, when integrated onto a tensegrity robot, will allow it to shape lock, or bear loads without collapsing. The tendon is made with a silicone membrane and torsional springs that provide a restoring force, and thin plastic layers that deploy inside the membrane which increase in friction upon presence of a vacuum and therefore increase longitudinal stiffness of the tendon. We characterize the VST with experiments to determine its maximum force, bending stiffness, and dynamic response to vacuum pressure. The design is almost finalized, and the tendon is now being integrated onto the robot. We anticipate that the robot will locomote normally with these new tendons added, but will now be able to stiffen and withstand the force of external weights such as a dumbbell.