I visited a thread and saw a dear designer’s work. He even sent his Rhino file that I downloaded and opened it. I noticed he used a sphere as his curvature surface base.
It was a lesson for me, but as I usually work with my method, I deleted all the surfaces that he made and kept the accurate sketch of the glasses.
I didn’t use a sphere but made the curvature surfaces with three separate single surface spans, and then did projection and other works. I don’t know, is it confirmed by the dear designer or not, but I just know his work would be more accurate and detailed than what I made.