Download and print the templates from sewmag.co.uk. Cut two body pieces and two top pieces from patterned fabrics. From fabric folded right sides together, snip out two fins and one tail piece. Layer these onto wadding and sew around, leaving the straight sections open. Clip the curves, turn out each piece, and press.

Tack a fin to the top centre of each body piece, before joining the top piece right sides together along the straight edge. Fold out, press, and topstitch 1mm from the seam. Cut two pieces of lining fabric to match the completed body pieces.

Join the linings to the top of each body piece, stitching across the top and 4cm down each side. Clip the corners and turn out the flaps at the top fully. Tack the tail piece to the bottom of one body piece, matching up raw edges, then pin both body pieces right sides together, matching up the flap seams. Sew all around, leaving a 7cm gap in the bottom edge of the lining. Turn out through this gap.

Fold in the raw edges of the gap and slip-stitch closed. Push the lining into the body. Fold over half the depth of the top flaps and topstitch to make two channels. Cut two strips of fabric, 3cm x 30cm each. Fold in half lengthways and sew from the centre point down to one end, tapering the stitch line as you reach the end. Sew the other side in the same way, starting 3cm from the initial centre point. Turn the tube out through the gap in the middle.

Fold in the raw edges of the gap and slip-stitch closed, then press. Thread a tube through each channel at the top of the bag and knot together on the outside with a neat reef knot so the top of the bag can be gathered. Add buttons to either side of the bag to create eyes.