A method for producing a composite mandrel (20) for use in creating a precise set of surface features inside a hot isostatic pressed (HIP) billet for producing a desired tool uses a composite nickel shell (16) and ceramic interior (18). A free form fabrication (FFF) or wax positive pattern (10) of the desired tool is made first, then a layer of nickel is deposited on the surface of the FFF positive pattern to produce a nickel shell (16) which is a negative of the desired tool. The final step in creating the composite mandrel (20) is filling the nickel shell (16) with ceramic material (18) to increase the rigidity of the nickel shell thereby forming a mandrel for use in an HIP process to make the desired tool.