How to make a 2D origami ball (balloon)

(page 6)

9th picture of 2D origami ball (water bomb)

09.

Apply the diagonal "valley-fold" of the step #8 and then unfold.

Prepare to apply another diagonal "valley-fold" and then unfold.

10th picture of 2D origami ball (water bomb)

10.

Apply the diagonal "valley-fold" of the step #9 and then unfold.

Prepare to apply four "valley-folds" .