The pantograph is the original scaling tool! It was first developed in 1603 so that Christopher Scheiner, it's inventor, could copy and scale diagrams with great precision. Something we now do in seconds with copy machines and computers was done entirely by hand back in the days of old. This pantograph was created to help students explore the concept of similarity in the geometry class. They can create 2D geometric shapes and then use the pantograph to trace their shape while watching the extendible arm draw another shape that is similar in every way (their corresponding angles are congruent and their corresponding sides are in proportion). Help your kids explore similarity and proportionality with this wonderfully hands-on tool!The rods were built from the ground up using SketchUp. The nut and bolt are a remix of the design posted on Thingiverse by naikrovek. To construct, follow the diagram here: http://www.ies-math.com/math/java/geo/panta/pantasetu.gif I hope you and your students enjoy! All feedback is welcomed!