The document discusses the pros and cons of using 2D versus 3D tools for concept design development. While 2D tools allow for the same representation as paper drawings and easier collaboration, they are less suited to concept design exploration and prototyping. 3D tools remove design ambiguity and enable digital prototyping, but are intended for detailed rather than conceptual design work and can have interdependencies that cause failures. The document promotes an integrated 2D and 3D solution to leverage the benefits of both during concept development and detailed design.