I figure out my upper and lower dimensions similar to a regular single panel, then add an extra 6” for the pleated portion. I mark out where the 6” pleated area will be with a chalk pencil. Mark it at the center point of the pleated area and make the folds. Sew the outer folds first, then sew the inner folds. If you are going to add the webbing like the Overwatch saddle, I would sew it on before I folded and sewed the pleat but stop about 1 inch from each end. Go ahead and sew on the binding around the whole saddle and Then I add a piece of 1” weeping inside to keep the pleat from extending all the way to the very end. This also reinforces the ends. That part is optional but I’ve noticed it makes them much stronger and haven’t noticed it causing any discomfort. Finally sew the prefabricated body onto your continuous loop of webbing (saddle chassis). Then you could sew the last one inch area of the two webbings used for the plastic triglides. One would be a loop for the linesman loop and the upper would be for attaching points of the leg straps. What I’ve found with pleated saddles, is that taking your time to line the body portion up properly and sew the pleat and binding in, takes longer than attaching the rest of the saddle components, at least for me