Hi Michael,

Thank you for your detailed description. That gave me a precise hint how to do it. I worked through all tutorials I could find on blend on youtube. But just now I realized, that the reason I could not do it was, that the extruded objects were solids... If I extruded them without caps, it worked like a charm... And blend does only work on edges, NOT on curves! Did not know that.

I changed the extrusion path of one curve and got it closed! Yes!!!

Before it was not closed. Only a joined surface. Is there some kind of auto repair or detection to find out where exactly your model is not closed?

I really had to get used to modeling with surfaces. Normally I model with solids only.

Alle the Best,
Philip