Approximate expressions describing shape efยฎciency are derived and two charts are shown that help with design. The ยฎrst is a failure chart that shows the complete set of possible designs (and lay-ups) that allow the complexity of the problem to be presented in a simple way. The second is a chart showing optimal lay-ups for a cylindrical shell subject to axial compression. The load-bearing efยฎciency of cylindrical shells derives from both the properties of the material of which they are made and from the shape itself. Generally, thin-walled or slender shapes are more efยฎcient (meaning lighter and more economical in the use of material) than thick-walled or solid sections. The limit in shape efยฎciency is either set by manufacturing constraints or, ultimately, by the properties of the material from which it is made. Laminated composite materials are more difยฎcult to analyse than conventional isotropic materials, such as aluminium alloys, because of the additional need to consider the variation of ply orientation through the thickness of the laminate. These ultimate limits are examined and determined by a balance between competitive failure mechanisms.