Abstract: Method of forming heat exchange panels in which a heat exchange fluid is circulated in flow passages between an inlet coupling and an outlet coupling. A panel is formed by welding together two facially-opposed deformable metal sheets to constitute a front sheet and a back sheet. Either the front sheet or both sheets are provided with a pattern of welded and non-welded areas outlining the flow passages which are expanded or "pillowed" by the injection of a high-pressure medium between the sheets. The method provides for the inflation of the outlined passageway by use of the same couplings and fittings used for the circulation of the heat exchange fluid.