In order to achieve the proper frequencies and coupling in Side Coupled Accelerator Structures, it is often necessary to model the cavities. In order to reduce the number of modeling steps and hence reduce machine shop time and cost, we have drawn heavily upon previous LAMPF experience and present day numerical calculation programs. Using a few aluminum cavity models at selected machine energies, we have been able to predict the frequency and coupling of our structures with good accuracy. This paper will describe the steps used to determine the cavity dimensions that meet our structure requirements. 6 refs., 6 figs.