Select external curves from contour

Hi everybody! :wave:
I created solid and wanted to select external curves on one side of brep after node Contour, but my brep is a hard solid with many faces and in result I had many curves.
I will be glad of any help (88.1 KB)

You can compute the dot product of the face normals and a manually defined vector which should be roughly perpendicular to the desired orientation of the object.

The similarity component can be used to find the normals which are parallel within the tolerance specified. (84.8 KB)