When I made one years ago I used a single sheet cut to size then sew on a gathered skirt around edge, of fabric I purchased, which measured twice the circumference of the bed and the width ,of course was from just above BASE height and to the the floor. But you could just make a wide -very gathered ruffle of fabric ,that has elastic along both sides,which would hold it in place, but you would need to make it perhaps two and a half times the circumference for a good ruffled effect.