Katje from Of Dreams and Seams shows how she created the side snap closure on a dress made from a vintage 1938 pattern. Fitwise, if serves the same purpose as a hidden side zipper, but uses sew-on snaps instead. She says she now prefers the snap version to a zipper for several reasons, including the flexibility in the length of the opening. Get the tutorial at Of Dreams and Seams.
[photo from Of Dreams and Seams]