The orange mark shows to apply the flat strip structures to the surface, but the curves have problem to create these flat strip due to their orientation.
Thank you so much Kim. That is very helpful. I taught about offset on srf, but do not know it needs to work with extend and pull curve knots. One more question, in order to achieve sharp finish like this, can trim work in this situation, I mean after ruled surface knot curve.3dm (123.0 KB) waffle_minsrf_re1a.gh (21.4 KB)