Abstract: A method and apparatus of forming a preform (12) of structural fibers (14) includes a hermetically sealed housing (18) for controlling air pressures and flow therein. A perforated screen (28) is located within the housing (18) separating same into a high pressure chamber (34) and a low pressure chamber (36). Pressurized air is supplied to the high pressure chamber (34) to agitate and randomize fibers (14), and a vacuum (26) is provided in the low pressure chamber (36) to draw and compact the fibers against the screen (28). The pressure differential between the chambers (34, 36) provides significant compaction of the fibers against the screen. A binder (16) is applied to the fibers (14) to maintain the shape of the preform.