I like this ruffle fabric lampshade idea for the girls' room, but am thinking it would make a great small shower curtain for their shower stall, as well.
Make pleated shade cover w/a patterned fabric & covered buttons. A No-Sew Pleated Cover Cut elastic to fit snugly around the top of a shade, and cut fabric to fit around the shade, allowing extra for hems. Hem bottom. Fold fabric top over; press. Place elastic on turned edge. Stretch and hold the elastic as you sew a zigzag stitch down the center. Sew fabric ends together.