Abstract: The present invention relates to a universal decorative covering case and method for modifying or altering existing horizontal or vertical blinds, louvers and the like. The universal covering case particularly is designed to conform to any preexisting vertical or horizontal louver assembly. In a preferred embodiment, the universal covering case of the present invention comprises a transparent case which is designed to individually enclose a slat of an existing vertical blind assembly, thereby creating a three-layer "sandwich" effect. On either one or both sides of the slat and between the slat and transparent covering case, a decorative insert is positioned. The decorative insert may be any web material that provides the desired decorative intent, such as paper, fabric, plastic film, and the like. The universal covering case can be easily and quickly installed onto any existing louver assembly without the use of any special tools or exceptional skills.