Is it possible to get the same mesh Box in Rhino V5 without the weird triangles along the edges?
I think all that should work- - make sure to mesh the boxy thing with ‘Jagged seams’ checked. Once you make the mesh, use Weld at 90 degrees and then SelNakedMeshEdgePt to make selection of the edge points simpler.
Also, if you have not, check out the Weaverbird plug-in.
especially the wbCatmullClark command, I imagine that might be of interest.
Thank you very much Pascal, yes it works, it seems that the only difference is in Minimum initial grid quads parameter, that in V5 needs to be changed from zero (and this is something that you already told me in the past). Also Mitch comment was helpful with UseExtrusions set to Polysurface in this Topic: Isocurve missing