A method of making a fibrous structural member including first, second, third and fourth portions, including folding first and second portions including continuous filaments about a first common fold such that the first and second portions are adjacent and substantially parallel to each other, folding a third portion about a second fold common with the first portion such that the third portion extends from the first and second portions at an angle thereto, and folding a fourth portion about a third fold common with the third portion such that the fourth portion is adjacent and substantially parallel to the third portion.