Merman's body

It's rather stout body.

Sew and stuff

Cut cotton cloth with 0.5cm allowance.

Sew the darts. Sew the middle of the back.
Sew sides.
Turn inside out.
Put the core into the neck. Same as mermaid.
Stuff with polyester fiberfill solidly.
Close the opening of bottom.

Make the valley of the breast with a thread.

Cover

Cut stretch fabric.
Sew and turn inside out.
Cover the base of the body with it, and stitch at the bottom.