A preform manufactured by an additive manufacturing process is provided. The preform may include an annular fibrous layer made from a polymeric material, such as PAN. The annular fibrous layer may comprise one or more of a non-uniform areal weight profile, non-uniform fiber volume profile, and a non-uniform fiber density profile. Such profiles may vary in either or both of the radial and axial directions, as well as in localized regions of the preform.