I?ve not received a solution for the other problem here, so I explain my own one. Hopefully that helps someone else. nIn order to produce a surface for the narrow wall, the selection of lines must correspond to a unique area. We cannot produce one surface for narrow wall in one step because if we select all lines surrounding the narrow wall, there will be other possibilities to generate a face and SpaceClaim chooses to produce a surface containing the narrow walls and the hexagonals between them. To resolve that, we can define two sets of lines each generating half of the narrow walls, but each set itself should not surround a hexagonal in it. Therefore, we will have two surfaces whose union is the desired narrow wall.n