An Illustrator script to generate the guilloche patterns found on BankSimple's website. Picks randomly from an array of "good looking" guilloche patterns and creates the paths to fit in the current artboard.
Play with the configuration values near the top of the file.
Download the script and open it in Illustrator (with a document open) by using File > Scripts > Other Script. If your computer is crap this will be a very slow, painful process.