Abstract: A flexible and resilient positive pattern is made for a desired high temperature metal or ceramic part such as a gas turbine impeller having a complex geometry with walls defining undercut spaces, and the pattern with flexible walls is dipped into a ceramic molding media capable of drying and hardening. The pattern is removed from the media to form a ceramic layer on the flexible pattern, and the layer is coated with sand and air dried to form a ceramic layer. The dipping, sanding and drying operations are repeated several times to form a multiple layer ceramic shell. The flexible wall pattern is removed from the shell, by partially collapsing with suction if necessary, to form a first ceramic shell mold with a negative cavity defining the part and to provide for reusing the pattern. A second ceramic shell mold is formed on the first shell mold to define the back of the part and a pour passage, and the combined shell molds are fired in a kiln.