The hat is a NURBS surface, it won't be exported to the obj file. Convert it to a polygonal surface then export. Modify>Convert>NURBS to Polygons>options. The "control points" tessellation option is pretty good especially if you want to keep the same edge flow. The new poly mesh will most likely need to be smoothed in some way. OMG thank you so much!! Finally I can keep working! As you said, the new mesh needs to be smoothed... Can you suggest me a good way to smooth it? Thanks again, you saved me.