Diagrams, or “The Art of the Line" A diagram is a linear representation of a three-dimensional object, which craftsmen follow to create the work. Framing or carpentry diagrams clearly indicate the various parts and show how they are to be put together. “Stereotomy” is the art of showing how stones are to be cut to specified sizes and dimensions. This method of drawing, something like a blueprint, shows the objects in plan (from the side), in elevation (from the front) and in projection.The technique of stereotomy was taught at Pierre-François Guillon’s school, officially titled “The Practical School of Stereotomy Applied to Construction,” later called the School of Drawing.