Im pretty experienced in 2d mechanical dwg. Trying to learn 3d. It seems the process of moving a shape between an object type of surface/mesh/solid and vice versa is not very straight forward. So the question is what is the preferred method of generating a somewhat irregular part when the end result needs to be a .STL file for use with a 3D printer? how would a pro draw something like a football that would be exportable as a STL file? or half of a football?