Work in st st until handle meas 60cm. Cast off.
Attach sides and base to front and back of bag. Fold handles in half and sew together using mattress stitch to form a tube. Attach handles inside of bag at both sides. Make a lining to fit inside of bag and sew into place around top edge of bag. Using 4mm needles and yarn A, cast on 42 sts. Purl 1 row. Change to yarn B. Work in pattern as for bag until work meas 16cm, decreasing 3 sts across last row. 39 sts. Change to yarn A. Next row: K1, *P1, K1; rep from * to end. Next row: P1, *K1, P1; rep from * to end. These 2 rows form rib. Work in rib for 4 cm. Cast off.
Fold case in half and sew down back seam, omitting rib. Sew across bottom, making sure back seam is in the centre. Fold down rib to inside and attach around top row to form a tube. Thread cord through tube around top and attach a toggle to secure.