A complex-shaped, three-dimensional fiber reinforced composite structure may be formed by using counteracting pressures applied to a structural lay-up of wetted fibers with mechanical features embedded or encapsulated therein. The mechanical features may be located on or at least partially between two or more pressurizable members, which may be internally pressurized within a mold. The mechanical features may operate as bearing plates, attachment fittings, or other structural elements. Assemblies of pressurizable members, fiber plies and mechanical features may be arranged to create complex composite structures with predefined load paths, enhanced structural capability or both.