" you have modelised in another "World"! (Polygons: segmented lines)
MOI is "Nurbs" lovely smooth curves! :)"

I agree, MOI has stunningly amazing lovely sweet smooth curves !

And what I want is the best of two worlds : Polymodelling gives me the advantage of beeing able to change the shape and try variations during all the process and it is a very intuitive way of modelling. MOI gives me precision and those lovely curves . . .

Disadvantage is the time effort tu build up the curves in MOI - projection is a good idea but I also have curves moving through x y and z planes.