 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.