PURPOSE: To provide a new method of manufacturing an article having a prescribed contour by superplastic forming and diffusion bonding.

CONSTITUTION: A plurality of titanium sheets 43, 44, and 46 are assembled into a stack 40. At least one of the sheets 44, 46 is provided with stop off materials 56, 58 on one of its surfaces 50, 54 to prevent diffusion bonding at predetermined positions. The edges of the sheets are welded together and a pipe 72 is welded to the stack 40 to interconnect with the stop off materials 56, 58 to form a sealed assembly. The assembly is heated and the inside is pressurized to diffusion bond the sheets 42, 44, and 46. The integrated structure so formed is heated and opposite ends of the integral structure are twisted relatively to contour the integrated structure to a predetermined shape.