Yesterday, I made a remix of the original project, adding pen strokes. The result is a static pattern. https://scratch.mit.edu/projects/421860943/ Here, I do the same thing to my earlier remix that uses sine and cosine functions for the movement. As you can see, the pattern is no longer static, but ever changing. To keep the background from getting too cluttered, the pen strokes fade away in this version.
Thanks to @heldlaw for the incredibly remixable original project! And thanks to all the others who have made cool and inspiring remixes (note that there is a delay of a day or so before a remix shows up in the remix list): https://scratch.mit.edu/projects/420987785/remixes/