I’d like someone really knows the guts of SketchUp to have a look at these 2 files. I don’t know SketchUp (I’m a Rhino developer) very well myself but it seems like you ought to be able to use the push-pull tool on either of them. In Rhino they are both meshes in the xy plane with corners at 0,0,0 5,0,0 5,5,0 and 0,5,0. The only difference is the one that doesn’t work is a single quad that is turned into a single face in the SDK. The one that does work is 4 quads in Rhino that get turned into a single face with the SDK. The interior colinear vertices of the second example are getting removed so both faces in SU should only have the 4 corner vertexes. Thanks.