source by Dan Anderson: https://www.openprocessing.org/sketch/519299
Enlarged and plotted on a Roland DXY pen plotter: 0.7 mm black pen on design vellum.
Even if the 0.7 mm pen is a bit chunky for fine guillochÃ© effects, the plotter output is pretty crisp. Here’s a detail at full resolution:
Unfortunately, an earlier attempt to print this figure using a fresh-out-the-box 20+-year-old HP SurePlot Â¼ mm pen on glossy drafting paper resulted in holes in the paper and an irreparably gummed-up pen. If anyone knows how to unblock these pens, I’m all ears â€¦