A method of providing a mould with a conformal cooling passage includes rough machining a mould cavity generally corresponding to a moulded part shape using CAD data. Conformal cooling slots are cut in the mould cavity using the CAD data. The conformal cooling slots are welded shut using the CAD data to provide conformal cooling passages. A class A surface is machined over the conformal cooling passage and corresponds to a finished mould part shape using the CAD data.