with no twisting or doubling up the shape of the apparatus 10 necessarily will have a cross section indeed the cross section of the wall 20 itself as well as the cross section of the gap 21 or space 21 in the center thereof may take on any suitable shape the number of shapes possible is a digit too high to begin to consider even a small fraction of the possibilities one may refer to fig2 for the shapes of several polygons these polygonal shapes may be the cross sections 22 of the wall 20 itself along the section a a of fig1 as illustrated nevertheless each of these shapes of fig2 also represents a possible shape for the interior surface 15 of the apparatus 10 thus with the wall thickness minimized and represented only by a line any of those shapes and more may represent the perimeter and outer of an apparatus 10 meanwhile any of the other shapes of nature plants animals houses buildings objects tools toys vehicles or the like may be the shape taken by the apparatus 10 when relaxed and unstretched a sheath 23 may be thought of as a decorative cover 23 for example an alternative mechanism for manufacturing an apparatus 10 in accordance with the invention may involve extrusion of the solid polymer in a cross section 22 illustrated for example a circular cross section 22 a square cross section 22 b triangular cross section 22 c and.