3B1B is incredible. I loved his video (https://www.youtube.com/watch?v=r6sGWTCMz2k) using Fourier series to make epicycle animations. I worked through the details to make my own: https://bldavies.com/blog/computing-epicycles/

For those interested, I explain some of the math involved in computing epicycles from sample data here: http://bldavies.com/blog/computing-epicycles/

Try this: https://obfuscator.albertnis.com

Somewhat related/shameless self-plug: I created an R package [1] that provides data on travel times between NYC subway stops. These data can be used to, e.g., visualise and analyse the subway network [2].

[1]: https://github.com/bldavies/nyctrains

[2]: http://bldavies.com/blog/how-central-grand-central-terminal/