Recuperators include a core which is commonly constructed of a plurality of relatively thin flat sheets having an angled or corrugated spacer fixedly attached therebetween. The sheets are joined into cells, sealed and form passages between the sheets. These cells are stacked or rolled and form alternate air (recipient) cells and hot exhaust (donor) cells. Compressed discharged air from a compressor of the engine passes through the air cell while hot exhaust gas flows through alternate cells. The exhaust gas heats the sheets and the spacers, and the compressor discharged air is heated by conduction from the sheets and spacers. The need for repeatability of construction of each cell assures that the final recuperator is economically and easily assembled. Examples, of such repeatability required includes length, height, thickness, weld size, weld position, weld splatter and others. The recuperator assembly method provides a cell and a recuperator having repeatability of length, height, thickness, weld size, weld position, weld splatter and others.