Shell elements can be created from NURBS closed curves or planar surfaces, but not from non-planar surfaces or open cuves.
We use external mesh generator (T3D) to generate shell elements’ mesh. In the Analysis settings you can change element size (in mm) to generate more dense and precise mesh (i.e. 150, figure above). The Element count argument is used only for beam elements (MIDAS doc in CZ).
Non-planar shell elements can be created from Rhino Mesh geometry. You can also re-mesh Rhino Mesh as mentioned above.