Thank you very much for your detailed response Cappellaiomatto.
Indeed, the Spline there in the Klein bottle was handcrafted.
I was in a hurry and if I worked longer on it manually it would be perfect.
Best regards

Hi. I have a question.
I like to use Spline Wrapper 3.0 im may topological meshes, with Sweep and a circle.
I upload an manual example.