many, many moons ago I worked for a manufacturer of roll up doors and screens, as a installation designer. for a door it's a rather easy process to scribe plain styrene to mimic the slats. each slat is about 2½" tall. or an easier solution is to purchase pre-scribed styrene. if your roll housing is visible to the viewer, it's shape is either squared or rounded in section (depending on manf.) with large gears on each end with either a chain or motor drive.
otherwise I believe I've seen a product for these on ebay.