An FFGL source that simulates six 555 timers at the component level (a capacitor, two comparators and a flip-flop each) and patches them into the X, Y and brightness of a television's deflection yoke. Nothing gets drawn as a shape. The picture is wherever the beam went, brightest where the beam was slowest.
This demo runs the plugin's shaders in your browser, so it needs JavaScript and WebGL2. The plugin itself, its source and its downloads are on its repository.