A system and method are disclosed for securing a blade to a blade post or handle base. The envelope defines an evacuated chamber, which houses an anode and a cathode. Each bypass line communicates with a nozzle bore in a turbine wall. The check valve portions 20 communicate with a packing space of the bag body 11 at the respective hypotenuses of the right-triangular areas. The rigid body core is formed and the resultant rigid body is determined.