atom, That is what an external call is ideal for dealing with. The pp2 would look for X.obj and the actual X.obj can be any mesh, all it must have is the name. Although it is looking bad to have single sided props and look thru the empty side in the preview window, the normals are rendered the same from either side. Unless you are going to but a different texture on the two sides, why double the prop size by making it two faced?