Hi!

It turned out that the triangular prisms integrated in my model are not causing visible creases (lucky me).

Nevertheless, thanks again for the hints - I'm having the feeling that this knowledge is needed, sooner or later :-)

best regards

Bernhard



P.S.: it took me a while to figure out how to create a triangular prism that has control points: you need to loft two adjacent lines and then extrude the surface. When instead extruding a plane polygon triangle or lofting two polygon triangles (with closed caps), then you loose the control points (because the control points of the individual surfaces don't align).