Hi Ralf,

> ....Loft with > 4 Rails/Giude curves...could help :)

I see - previously you didn't mention that you wanted 4 guide curves.

In MoI, the Network tool can produce a surface from 4 guide curves, like this:



Just select all 4 curves and run Construct / Network to get that result.

If that's not what you mean by "Loft with guide curves", you're going to need to post an example model or describe it with a bit more detail.

- Michael