Then, you can use a reverse Axis transformation. [image: VgWn_Transformxyplane2.jpg] The following code would for instance transform any given face to be in the XY plane, with its barycentre at the Origin. axes = face.normal.axes origin = face.bounds.center t = Geom;;Transformation.axes(origin, axes[0], axes[1], axes[2]).inverse Sktechup.active_model.entities.transform_entities t, face The drawback of the above method is that the orientation of the transformed face in the XY plane is not predetermined. So, if you wish to have a privileged direction, for instance an edge of the face to define the X axis, then use the following code instead, which will ensure that the selected <edge> defines the X axis, and that the Origin corresponds to the Start vertex of the edge. origin = edge.start.position xvec = origin.vector_to edge.end.position zvec = face.normal yvec = zvec * xvec t = Geom;;Transformation.axes(origin, xvec, yvec, zvec).inverse [image: 23wv_Transformxyplane.jpg] Note that you can use the transformation <t> to calculate the coordinates of points to reconstruct a copy of the face, instead of transform it. entities = Sketchup.active_model.entities face.loops.each do |loop| f = entities.add_face loop.vertices.collect { |v| t * v.position } entities.erase_entities f unless loop.outer? # for holes end Hope this help! Fredo