Methods and systems are disclosed for encasing various structures with a seamless continuous sleeve, where the presence of existing supports does not allow slipping a sleeve over the structure. In these methods strips of fabrics smeared with or saturated by resin are helically or non-helically wrapped or placed around desired shape mandrels that are located around a support of the structure. As the resin is partially cured, a portion of the sleeve segment is moved away from the mandrel, leaving the rest of the sleeve on the mandrel to be attached to the next will-be-fabricated sleeve segment. The process will continue as many times as needed to create a sleeve of a desired length. In various embodiments the strength of the sleeves varies at different locations. In some embodiments the gaps between the sleeves and the structures are filled with gas, liquid, solid, or any other materials.