Hey Michael,

Thank you so much for your explanation, this is very helpful!

I did what you suggested and have made some progress but am now a little stuck. I managed to create this:


The problem is when I use the blend command, it creates a bulge:


And to complete the adjacent sides, I created another curve and extruded it:


I can't figure out how to properly (and elegantly) intersect the extrusions and form a solid.

Thank you for your brilliant support!
Gunter