A portable structure or hunting blind includes a floor railing or frame system for supporting side walls and a roof. The side walls and roof are formed of polyurethane foam. The side walls and roof can be manufactured by applying uncured polyurethane foam over a sheeting material, which is supported by a removable set of forms. The polyurethane foam is then allowed to cure, and once cured the forms are removed. A door and windows and floor decking can then be installed to finish out the hunting blind. The exterior of the polyurethane foam walls and roof can be coated with an elastomer coating for UV protection.
