This paper introduces a fully compliant spherical joint with a stiffness profile specifically optimized for balancing a pendulum. The design builds on previous work where a fully compliant spherical joint was created using tetrahedron-shaped elements connected in series. Using a numerical simulation, optimizations are conducted for two different ranges of spherical motion. Based on one of the optimized results, a prototype is fabricated and experimentally validated, achieving a moment reduction of 90.5%. The deformation calculated by the computational tool closely matches the prototype’s deformation with an accuracy of 89.6%, demonstrating its potential for application in the development of shoulder exoskeletons.