One edge together with the faces on either side of it. An edge with two faces is interior, one
with a single face is on an open boundary, and one with more than two indicates non-manifold
geometry - which is the usual reason a shape refuses to become a solid.
One edge together with the faces on either side of it. An edge with two faces is interior, one with a single face is on an open boundary, and one with more than two indicates non-manifold geometry - which is the usual reason a shape refuses to become a solid.