Abstract: A method of connecting a first shell to a second shell to establish a unitary sealed structure. A bead of a diaphragm assembly is connected to a first peripheral surface on the first shell to establish a first sealing surface and to define a first chamber between the diaphragm assembly and the first shell. A spring attached to the diaphragm assembly engages the second shell. A force applied to the second shell compresses the spring to bring a second peripheral surface thereon into engagement with the bead on the diaphragm to establish a second sealing surface and define a second chamber between the diaphragm assembly and the second shell. A vacuum evacuates air from the first and second chambers to establish a pressure differential between the first and second chambers and the surrounding environment. This pressure differential acts on the first and second shells to urge the first and second peripheral surfaces against the diaphragm to establish a unitary structure.