What I did with the acrylic was just to machine stitch down the fell like I would a knife pleat I was sewing with a machine, right down both edges. If I was hand stitching wool, (unlikely, as my hands would not take doing a garment the size of a kilt) I would stitch from the back. I'd use small stitches too. I'm interested to see what the knowledgeable folks have to say.