Set squares are drawing instruments used to create vertical, horizontal, and diagonal lines as well as certain angles. They may be shaped as squares, Ls, or triangles, although in American usage set ...

Use a pen and ruler to draw over the vertical lines and join the dots, giving you a square. Image caption, Use a pen to draw a dot where the arcs meet directly above the original horizontal line.

although recently computer-aided drawing has largely superseded the use of instruments for drawing by hand. The mathematics collections document the stories of several of these objects individually, ...