Step 16
: Slide the head.Make a mountain fold on the dotted line(a-a’) as shown below.
Step 17
: Make a crease.
Step 18
: Make a crease.
then unfold.

Step 19
: Make an inside reverse fold on (b) and pull out (a).If you unfold the model, it will be easier to fold it.
Step 20
: Make an inside reverse fold on (b) and pull out (a).If you unfold the model, it will be easier to fold it.
Step 21
: Fold a thin layer behind,repeat behind.
Step 22
: The origami duck is done.