A single level masking process for producing microelectronic structures, such as magnetic bubble domain devices, which require very fine line widths. This is a subtractive dry process using a very thin, additively plated mask in order to obtain optimum lithographic resolution. Use of the very thin plated mask eliminates the need for a thick resist layer which would adversely affect resolution. In one example, a double layer metallurgy comprising a conductor layer (such as Au) and an overlying magnetically soft layer (such as NiFe) is patterned using a thin Ti (or Cr) mask. The Ti mask is subtractively patterned using a NiFe mask which is itself patterned by electroplating through a thin resist layer. The double layer NiFe/Au structure is patterned to provide devices having high aspect ratio, good pattern acuity, and uniform thicknesses, where the minimum feature is 1 micron or less.