Rigidifiable composites are formed by stitching a reinforced B-stage resin sheet stock to form a three-dimensional preform. The preform is subsequently rigidified by initiating final cure of the resin. Molded articles, inflatable and other structures, such as, tank, tunnel and sewer liners are some of the typical structures which can be formed by the methods of the invention. Control of thread count, thread tension and thread spacing can be used to consolidate multi-ply or layered preforms, which, upon cure, can have up to 90% of the load carrying capacity of compression molded fiber reinforced articles.