I have never had any issues saving a copy as a .STL file before. This morning I tried to do that and the STL option doesn't even show in the drop down. The file I'm trying to use has been used before and created an STL fine. Now no matter where I pull it from as a .prt, step or iges, I don't have the option to create an STL. Am I missing something? I had other engineers try it on their systems as well to no avail.