Maybe you’ve built your own drawing robot, but I doubt it comes with a geometric pun like the Isoscelease pen plotter device. As the name would imply, this robo-plotter uses a constantly varying isosceles triangle that is able to angularly expand and contract as well as move as a unit back and forth. This allows for an innovative way to move in the “X” and “Y” directions. One limitation is that this plotter doesn’t have a way to pick the pen up, however, as seen in the video below, it can still draw a beautiful image.
To drive this motion, a servo motors powers a belt drive for each of the two arms. As noted on Darcy’s page, the belt is in tension, while the linear rail that it rides on is compression, giving nice rigidity to the design. The resulting movement is quite nice, and I could see this type of setup being used in a different context like a pick-and-place robot, or even a 3D printer.
Currently, work is being done to generate pen paths for portraits using Processing.org. I’d never heard of this site before, but according to its description, it was originally created to “created to serve as a software sketchbook and to teach computer programming fundamentals within a visual context.” This might be an interesting resource to check out for those that want to bring their projects to life. I’m a fan of Python in my limited programming experience, but there’s almost always more than one way to do something like this.