While vising Tom Tits Experiment recently with the family, we saw an interesting experiment using a harmonograph. It was built with two big pendulums and a BIC pen, and it produced quite nice images, like this one:
I decided to try to replicate it virtually (not knowing anything about harmonographs or the curves they're designed to generate), and I came up with Penduolum:
The link to the project demo: https://valdes.cc/penduolum/
And the source code: https://github.com/jonvaldes/penduolum
Penduolum uses Notan as a general framework, and egui for the UI.
Thanks to my friend Nazarí González for the help and for building the Notan!