With 6mm needles and A cast on 23sts.
Work in double moss st as for the bath mat increase 1 st at each end of 3rd and every right side row until there are 59 sts.
AT THE SAME TIME working in stripe sequence of 4 rwos A, 2 rows B, 4 rowsA, 2 rows B, 4 rowsA 2 rows C.
Work until 30cm, then decrease 1 st at each end of every right side row until 37sts remain.
Work casing stitch closely round edges omitting cast off edge. Thread elastic through casing and secure ends at the ends and cast off.