Three dimensional drawing on a two dimensional screen is difficult conceptually and even more difficult in practice. In addition, only 15% of most CAD work involves three dimensional work (IDC '87 data). Most people need only two dimensional capabilities. When three dimensional work is needed, a two dimensional Claris CAD drawing can be easily transferred via IGES or DXF to a high-end three dimensional CAD package.
Claris CAD is extremely useful for those who want to do their drawing quickly and accurately. Many users use Claris CAD to do 2-D drawings that they then import into 3-D programs. For example, a user may do the basic drawing in Claris CAD, translate the file to DXF and open it in AutoCAD to do his 3-D rendering. There are also programs that will open a Claris CAD file and extrude it into 3-D, such as ModelShop (Paracomp).