This Trim Fast mitered crown mouldin inside corner, which works with our 8 ft. Trim Fast moldings, is ideal for DIY projects and offers professional results without the need for expensive power tools. Whether it is classic or contemporary, American Pro Decor peel off and stick polystyrene plain crown moldings encompass a great selection of period correct designs, patterns and sizes for a wide variety of applications. Plain crown moldings are used to decorate a ceiling in many creative ways adding an architectural focal point to any room with style and beauty. Plain crown moldings are extruded showing extreme care for its crisp lines which provides an elegant detail. They are lightweight, strong and easy to install using standard wood working tools.