Dust and fading is a concern. If I had to store my fabrics out in the open, I would just use an old sheet to throw over it until I felt like tackling a permanent solution. When I felt like it, I would measure a piece of material wide enough and long enough to cover my stash. I would fasten the top edge of the fabric to the wall behind the shelf. I would put a gusset for a dowel or cardboard tube on the bottom edge. When I wanted to get into my stash, I would roll up the material on the dowel and lay it on top of the cupboard.