This is the Polarplot: a 3D printable SCARA plotter with a 5-link parallel mechanism and an Arduino based controller. It ships with a custom developed software for operation (PolarPlot). You can attach a pen or marker to this robot to draw geometric patterns and a lot more.
You can use something like this for laser engraving as well. The digital kit comes with STL files that you need to print this robot and put it together yourself. PolarPlot supports freehand drawing but you can also import external SVG files.