Abstract: The height of a layer of material formed by molten metal disposition is measured by ejecting the material as elongate extrusions and measuring the time required for each extrusion to contact the workpiece, then using this time interval along with the speed at which the extrusion is ejected to measure the gap between the ejection head and the workpiece. This gap is then used for calculating the height of the previous layer. By making the workpiece and the ejected material electrically conductive, this time interval can be measured by noting when electric current flows through the extrusion.