Abstract: This invention discloses structural reinforcements for glass-ceramic matrix products, such as in heat exchanger matrices of the regenerator and recuperator types. In such matrices, a structural improvement is provided as follows: (1) In a regenerator wheel having parallel, open air passages through it, certain passages in areas of the periphery or hub are filled with a finely divided material, such as a ceramic or frit of the composition of the matrix. The composite of the matrix and fill material therein is heat treated or cured to unite the matrix and the material. This filling or "stuffing" converts the honeycombed matrix region to a structurally reinforced portion of the device.