The cleverest but least pretty solution I have seen for that is to screw a row of plastic roll-end shipping supports to a long plank, then cover the vertical rolls with left over media boxes with one of the ends cut off. Very important that the rolls are wound tight to prevent sagging, and make sure the screw heads are placed to not mar the ends of the rolls thereby causing head strikes. In the deluxe version the plank is placed on a table or very sturdy shelf rather than on the floor.