Im running Mill Standard and need to machine a surface,( atttached ) I tried Z rough in 2D and 3D. Cant get either to pick the surface. It originally was a txt file from Mach 3 digitizer wizard. Ran in MachCloud to convert to STL. Then opened in MashLab to convert to a STL bobcad can open. Saved as bccd. and tried to do tool path, but cant get past select geometry. Any info would be greatly appreciated.