A new optical design procedure for designing an optical device that will duplicate the wavefront errors of another optical instrument over the full field of view is described in this paper. We call this optical design procedure the inside-out method. It was devised to design an optical instrument that generated wavefronts simulating those of the Hubble Optical Telescope assembly (OTA). As is now common knowledge, during fabrication the OTA primary mirror was made using a defective null-test device; therefore the oTa wavefronts showed perceptible spherical aberration. With the inside-out method it was possible to design an instrument called Red-2 Stimulus that matched the OTA aberrated wavefronts to less than 0.0005? (638 nm) peak to valley on axis and 0.006 X maximum over the full field of view. The inside-out method is described, and two illustrative examples are given.