How to make a narrow deep origami box

(page 9)

15th picture of narrow deep origami paper box

15.

Tunr the model over.

Prepare to apply a horizontal valley-folds and then unfold.

16th picture of narrow deep origami paper box

16.

Apply the horizontal valley-folds of the step #15 and then unfold.

Prepare to apply two valley-folds only on the front-most layer.