A mobile apparatus for measuring thickness of a coating on a surface of a substrate comprising: a coating thickness monitor for measuring the thickness of at least a portion of the coating on the substrate, said coating thickness monitor including: (i) at least one radiation source for providing radiation to be directed towards at least a portion of the coated substrate, (ii) at least one probe for directing said radiation at said at least a portion of the coated substrate and for capturing at least a portion of the radiation reflected and refracted by the coating on the coated substrate, the captured radiation being at least a portion of the radiation directed towards the coated substrate from said radiation source; (iii) at least one detector in communication with said at least one probe, said at least one detector capable of processing the captured radiation to allow a determination of at least the thickness of the coating on the substrate; and (iv) a means of anodizing the substrate to form the coating on the substrate; characterised in that: the monitor additionally comprises an optical switching system capable of transmitting said provided radiation to said at least one probe and said captured radiation from said at least one probe to said at least one detector; the monitor allowing determination of the thickness of the coating on the substrate at a plurality of locations; and the means of anodizing comprises a continuous volume of electrolyte comprising different zones wherein different current levels can be applied to each of said different zones. a coating thickness monitor for measuring the thickness of at least a portion of the coating on the substrate, said coating thickness monitor including: (i) at least one radiation source for providing radiation to be directed towards at least a portion of the coated substrate, (ii) at least one probe for directing said radiation at said at least a portion of the coated substrate and for capturing at least a portion of the radiation reflected and refracted by the coating on the coated substrate, the captured radiation being at least a portion of the radiation directed towards the coated substrate from said radiation source; (iii) at least one detector in communication with said at least one probe, said at least one detector capable of processing the captured radiation to allow a determination of at least the thickness of the coating on the substrate; and (iv) a means of anodizing the substrate to form the coating on the substrate; (i) at least one radiation source for providing radiation to be directed towards at least a portion of the coated substrate, (ii) at least one probe for directing said radiation at said at least a portion of the coated substrate and for capturing at least a portion of the radiation reflected and refracted by the coating on the coated substrate, the captured radiation being at least a portion of the radiation directed towards the coated substrate from said radiation source; (iii) at least one detector in communication with said at least one probe, said at least one detector capable of processing the captured radiation to allow a determination of at least the thickness of the coating on the substrate; and (iv) a means of anodizing the substrate to form the coating on the substrate; characterised in that: the monitor additionally comprises an optical switching system capable of transmitting said provided radiation to said at least one probe and said captured radiation from said at least one probe to said at least one detector; the monitor allowing determination of the thickness of the coating on the substrate at a plurality of locations; and the means of anodizing comprises a continuous volume of electrolyte comprising different zones wherein different current levels can be applied to each of said different zones. the monitor additionally comprises an optical switching system capable of transmitting said provided radiation to said at least one probe and said captured radiation from said at least one probe to said at least one detector; the monitor allowing determination of the thickness of the coating on the substrate at a plurality of locations; and the means of anodizing comprises a continuous volume of electrolyte comprising different zones wherein different current levels can be applied to each of said different zones.