In the field of compliant mechanisms, neutrally stable mechanisms are gaining interest for among others increasing actuation efficiency, vibration isolation and their use in metamaterials. Prestressing these mechanisms is necessary to provide the potential energy they require to reach their state of neutral stability. Current prestressing methods are limited by their need for individual application or relatively long activation times and limited reversibility, limiting mechanisms which utilize a multitude of neutrally stable flexures. This research aims to design a neutrally stable, enclosed volume joint on which prestressing utilizing a negative internal pressure is tested. The joint is first characterized together with a parameter study, used to understand the influence of its geometry, and a finite element model, to assess its predictive accuracy. An experimental setup is constructed, which measures the torque-angle behavior of the joint under different prestress conditions. The results are compared to the expected behavior, which is closely resembled for some of the prototypes, while the simulations prove to be only indicative of the general trend.