Just watch! Notice how the line never crosses itself. The knobs move with the drawing. (Use Turbo Mode to skip to the end.) If you like this, see the original project here: https://scratch.mit.edu/projects/93253024/ To produce the image, I converted a source image file into x and y coordinates, then calculated the optimal path through the points, by solving this as an instance of the Traveling Salesman Problem.
skin now added
