Hi Pilou,

> Does the "blue curve" is building by "Nurbs" curves along the intersections of the gride ?

Yes, I used Freeform curve through points.

> How are the nature of the extremities of this curve ? No tangent, tangent,...

I don't know I'll have to check it was something I did quickly without checking tangency, back in the day of the drawing board we used French Curves to draw through the intersection points.

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