How to make a regular octagon out of square paper

(page 9)

15th picture of regular octagon out of square paper

15.

Apply the slanted valley-folds of the step #14.

Make sure that crease lines are aligned along the dotted lines.

Prepare to unfold.

16th picture of regular octagon out of square paper

16.

Unfold the previous valley-fold.

Prepare to apply three valley-folds and then unfold.

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