A method for producing structures from composite materials, the method including forming a three-dimensional preform including at least one skin and a plurality of protrusions extending from the at least one skin, folding the three-dimensional preform such that at least some of the plurality of protrusions lie adjacent to either another one of the plurality of protrusions or the at least one skin and applying resin to the folded three-dimensional preform and curing, thereby to produce the structures from adjacent pairs of the protrusions or from some of the protrusions and the at least one skin.