[Jun8]

This is a good idea! The problem with these squiggles is that they look abnormal and would draw attention. It would be interesting if these can be tweaked somehow so that they are still bot readable but can also be interpreted as patterns by humans.

[TheLoneWolfling]

...Here's a crazy thought.

Take handwriting, the more illegible the better. Then use a genetic algorithm where the fitness function is trying to find as small a perturbation as possible to the input such that the output is recognized as the letters you want.

[xerophyte12932]

What if... we combine them with normal looking letters to make a captcha? humans see one thing, bots see some more?