Dear everyone, Currently I had a file with contour lines (two mountions, with correct elevation for each contour line). I need to creat a surface based on thoes lines. I tried to creat the 3D surface with LOFT command in AUTOCAD 2007. It was very slow to generate this surface. Do you guys know some other ways to creat the surface. My ultimate result need to be 3D surfaces for mountions and save in ACIS (SAT) format. Thanks for help. Best wish Pin