Here's a good look at the pleats on one of my kilts.

You can see the edges that are sewn on the outside (they are also sewn on the inside but you can't see that). You can also see the stitching done from the top to the fell. On this particular kilt that was done by hand but you could do it with a machine if the material was light / thin enough.

Oh, and welcome to X-Marks by the way!