An apparatus and method for magnetron sputter coating of an interior surface of a hollow substrate defining at least one irregular contour. The apparatus may contain a vacuum chamber and a target containing one or more metals having an exterior surface defining at least one irregular contour. The exterior surface of the target may be configured to conform to at least a portion of an irregular contour of the interior surface of the hollow substrate to be coated. A magnet assembly may be supplied which may include a plurality of magnets where the magnets are positioned substantially within a metallic target alloy.