Collapsible and portable cot type bed for pets and children. The selection of optimal phase shape widths is achieved by providing a lithography metric that describes the relationship between phase shape width and the target image dimension such that the metric, such as process window or across chip linewidth variation, is optimized. Control patterns are printed at fixed exposure dose and focus settings on a production substrate, and width is measured near the top and bottom of the resist layer thickness. The first edge abuts against the second edge to define a seam. A spreading arm is configured to apply force to the backing so as to flex the backing from the curled shape to the uncurled shape. Preferred methods of the invention can provide a more rapid and efficient cold start to the fuel cell vehicle.