I recently saw a commercial about a book on cabinet making. one of the perks of buying the book was the inclusion of a plan for a "box" that would enable the builder to cut strait lines with a circular saw. It looked like the saw fit into the box which you could slide down the length of the sheet or board that you are cutting, much like a table saw, only the saw was mobile. Does anyone know of this? Where can I get the plans for this?