Variant 1. 1 seat, 60 degrees curvature as made in Rhino. 

Variant 2.

Variant 3. 

Variant 4. 

Variant 5. 

Variant 6. Very nice curvature, attractive.

Variant 7. Model made as 3D example of a concept made by Luuk. To look if shape can stand on its own. This is possible if the back rest has enough curvature and when there is enough weight onder the seating area to keep the chair in balance.