Pleatsss.......

The hand made pleats are made by using a mold (also called frame or form), of which there are two layers, inside and outside. You lay the fabric in between the scored and folded oak tag, roll it up and steam it in an oven. On some fabrics, chemicals are used to enhance the effects.
Pleating molds are expensive and time consuming to make and one tiny mistake in one fold ruins the whole thing and you have to start over