An embodiment of an apparatus includes means for peripherally welding a cavity-back blade and a cover of the cavity-back blade to form a 3-dimensional hollow blade assembly, and a plurality of bellows contained in one or both of a first die half and a second die half receiving the 3-dimensional hollow blade assembly. The plurality of bellows are disposed within the region defined around or inward of the peripherally welded interface of the cover and the blade. At least a portion of the plurality of bellows are arranged in a manner to provide pressure to the cover at approximately a 90 degree angle to each of a plurality of nodes, each node defined by an intersection of two or more ribs in the cavity-back blade.