reddit

“
Banknote patterns fascinate me. I can get lost for hours in all the details, seeing how the patterns fit together, how the lettering works, the tiny security ‘flaws’ - they’re amazing. Central to banknote designs are Guilloche patterns, which can be created mechanically with a geometric lathe, or more likely these days, mathematically. The mathematical process attracted me immediately as I don’t have a geometric lathe and nor do I have anywhere to put one. I do, however, have a computer, and at the point I first started playing with the designs (mid-2004) Illustrator and Photoshop had gained the ability to be scripted. So off I went, using the hypertrochoid equations on Mathworld to create rather rough and ready patterns - scripting at this point didn’t have a very usable set of functions for creating beziers, so I had to use crummy line segments. The process took ages and served just to prove to me that I could do it, but the results were too poor to go much further.
” source...