Nature (corrugated sheet).
Fold the base form a triangle. Fold the triangle.
Fold the top corner and the lower side of the line of inflection. Turn over.
Lower the side toward the middle, pulling a piece of paper on the other side of the work.
Fold the top corner and the lower side to the middle.
Bend the upper part of his own. Concave corners, opening a job.
Fold in half.
Fill the corners (both at once) under the fold.
From autumn leaves can be up to the track.