a method for chemically milling an etchable workpiece by exposure thereof to an etchant in order to mill selected etchant - active areas and thereby form a plurality of raised die elements separated and bounded by a plurality of recessed cavities , which method is comprised of the steps of initially , partially etching the workpiece to form recessed die element precursors separated and bounded by recessed cavities , depositing a film of an etchant - resistant composition on the workpiece in at least selected ones of the recessed cavities , filling those selected cavities with an etchant - resistant filler and then subsequently processing the workpiece . in a highly preferred embodiment , the method comprises depositing a thin film of gold on the workpiece , removing the gold film from selected areas where active etching is to occur , and then filling the recessed cavities with an epoxy filler .