The present invention generally relates to an integrally woven three-dimensional preform with at least one sidewall in at least one direction constructed from a woven base fabric comprising two or more layers, and a method of forming thereof. A plurality of fibers in a first direction is interwoven between at least the top layer and a second layer, such that top layer is foldable relative to the other layers and form, upon folding, an integral sidewall. A plurality of fibers may also be interwoven between the second-from-the-top layer and a second layer, such that the second-from-the-top layer is foldable relative to the other layers, upon folding, form a second integral sidewall perpendicular to the first integral sidewall. The preform may optionally comprise a plurality of non-integral sidewalls formed by folding portions of the topmost layer.