I can import all the lines satisfactorily into SU. I could easily create a kind of terraced appearance by making surfaces and raising each by a metre at a time, but that won’t represent a realistic impression of the gradations.
Suggestions can include native tools as well as extensions.
That’s interesting. The inbuilt sandbox tools work very well but if you start with contour lines in the same plane (as I did), you do have to spend time moving them. The extension seems to speed this up by allowing you to ascribe height data to the lines. Is that the main advantage?
I also think that TopoShaper creates a quadrilateral mesh instead of the heavily triangulated one by the Sandbox from Contours tool. Both have their uses.