Abstract: A method of preparing a durable air-permeable mold having dimensional accuracy and without cracks clue to the segregation of the ingredients of the aggregate and without a surface irregularity, which comprises compounding 100 parts by weight of an aggregate obtained by compounding metal powders with metal oxide powders in a weight ratio of 5:95 to 30:70, the metal of said metal oxide powders being the same as that of the metal powders, 80% or more of said metal powders and said metal oxide powders having grain sizes of 300 .mu.m or less, with 10 to 35 by weight of an auxiliary hardening material that is softened and melted during the sintering process, and 10 to 25 by weight of a binder that contains an evaporable component, mixing them to form a slurry mixture, pouring it in a pattern mold to obtain a mold, drying the thus-obtained mold, and sintering the dried mold in an oxidative atmosphere at a temperature of 600.degree. to 1200.degree. C.

Abstract: A method for manufacturing shaped articles of organic substance is disclosed, which comprises mixing an organic substance as raw material with a binder, filling a die with the resultant binder-containing mixture, compressing the mixture in a prescribed shape in the die, and forcing a gaseous curing agent through the compressed mixture thereby curing the binder in the mixture and consequently solidifying the compressed mass. This method enables shaped articles such as noise absorbers, heat insulation panels, and plate materials to be produced efficiently and inexpensively at low energy consumption by the use of an inexpensive die.

Abstract: Proposed models are used for forming into destined shapes liquid, slurry, soft, sheet or lump materials, and are provided with endurance for many times of use and excellent permeability. A basic feature is that aggregates are ferrous or non-ferrous metallic grains and ceramic grains, to which a binder contained in evaporating or consumable substance is added and kneaded, and sintered. The mode has a close hardened layer scattered with metallic oxides on at least a shell. The hardened layer has fine air vents in its thickness. The whole body of a model is 5 to 60% of porosity and more than 100 Kg/cm.sup.2 of compression strength.