It takes a lot (or at least for me), determination. When thinking about an object, you have to think way ahead to figure out what tool to use. Modeling a cross section complete would involve many hours (at least for me it would). All CAD programs go at things a little differently. Turbo CAD relies heavily on how well you model your 2D profile. If your 2D profiles are not right, then your 3D will be almost impossible to master.