Ok - well unfolded in imagination before you, you have the backings strip. You lay the strips of denim onto the backing strip with a small hem already folded under and sew through both layers from the base of the fell to the lower edge.

Now visualise folding the backing material out of sight so bringing the strips of denim together at the top. Perhaps you might use half inch tape to sew through and join together the top of the kilt where it is shaped to narrow it into the waist. The same tape can be sewn horizontally along the top of the backing strip to cover the raw edges.

You now sew onto the edges of the pleats - from waist to lower edge pieces of backing material to form the under apron pleat and under apron on the right side and the under apron pleat on the left, then the denim apron.

If your backing material is not very heavy you could use it doubled, so the lower edge will not require finishing.

Anne the Pleater :ootd: