<P> Although drafting is sometimes accomplished by a project engineer, architect, or shop personnel (such as a machinist), skilled drafters (and / or designers) usually accomplish the task, and are always in demand to some degree . </P> <P> Today, the mechanics of the drafting task have largely been automated and accelerated through the use of computer - aided design systems (CAD). </P> <P> There are two types of computer - aided design systems used for the production of technical drawings" two dimensions ("2D") and three dimensions ("3D"). </P> <P> 2D CAD systems such as AutoCAD or MicroStation replace the paper drawing discipline . The lines, circles, arcs, and curves are created within the software . It is down to the technical drawing skill of the user to produce the drawing . There is still much scope for error in the drawing when producing first and third angle orthographic projections, auxiliary projections and cross sections . A 2D CAD system is merely an electronic drawing board . Its greatest strength over direct to paper technical drawing is in the making of revisions . Whereas in a conventional hand drawn technical drawing, if a mistake is found, or a modification is required, a new drawing must be made from scratch, the 2D CAD system allows a copy of the original to be modified, saving considerable time . 2D CAD systems can be used to create plans for large projects such as buildings and aircraft but provide no way to check the various components will fit together . </P>

10 types of lines used in drawing in cad