Abstract: A method and apparatus for making a preformed maskant sheet having a plurality of perforations corresponding to a pattern of perforations desired in a structure. A shaping surface is prepared on a sheet having the contours of the structure to be perforated. The surface is perforated in the precise desired pattern. A plenum is secured and sealed to the back of the shaping sheet, enclosing all of the perforations. A line for introducing air into the plenum is connected to the plenum. A coating of maskant material is sprayed onto the surface (which has mold release properties) while positive air pressure is maintained in the plenum. Air flows out through the perforations, keeping them clear of maskant. The maskant is then cured and the resulting self-supporting sheet is removed from the surface and placed against the structure to be perforated. The holes may then be formed by any suitable method, such as grit blasting etching or the like.