Hi gunter, I'd probably try Loft with the "Loft Style = Loose" option.

To do it, copy the bottom profile up a bit, and create a point object that's in the same plane as the upper profile like this:



Then select the profiles in order, bottom one first, then upper one, then the point object. Then run Construct > Loft and set the "Loft Style" option to "Loose" like this:



- Michael