Abstract: An interior design system comprising a display assembly having three flexible transparent overlays, a plain background sheet hinged to corresponding edges of the overlays, and a template sheet hinged to a free edge of the background sheet and having "scale" background and foreground grid sections for assisting in laying out interior room decorator's designs with a comprehensive catalog of design elements printed with scale designs of perspective furniture and accessory designs, and architectural elements for creating the room space to be decorated. The catalog pages have rows of printed scale designs covered with transparent plastic, with overlying, selectively removable and replaceable design elements with designs that are printed to the same scale on carrier sheets of flexible "static-cling" material, the carrier sheets being rectangular sections that are cut from a printed sheet the same size and shape as the backing sheet.