Abstract: A method of making an investment casting by forming a pattern which has the shape of the part which is to be made and forming from the pattern a mold of elastomeric (rubber) material which has a cavity which has the shape of the of the part or casting to be made. Liquid aqueous (water) material is poured into the mold cavity and the mold is cooled so that the material is frozen (ice) to form a solid temporary pattern having the shape of the part. The temporary pattern is coated or invested with ceramic material to form a solid shell about the temporary pattern. The solid temporary pattern is melted and the resulting aqueous material evacuated from the shell to form a cavity which has the shape of the part or casting. The shell cavity is filled with molten metal which is allowed to solidify to form the casting which is removed from the shell.