[cos_a + ux**2 * (1 - cos_a), ux * uy * (1 - cos_a) - uz * sin_a, ux * uz * (1 - cos_a) + uy * sin_a], [uy * ux * (1 - cos_a) + uz * sin_a, cos_a + uy**2 * (1 - cos_a ...

You can specify profiles in any consistent order: if necessary, skin() reverses the faces to ensure that the final result has clockwise faces as required by CGAL. Note that the face reversal test may ...