I've always liked doodling on graph paper. I like making interesting patterns by drawing lines between the intersections. This is basically automated graph paper.
This is the 6th ish iteration of this project. It was my first real programming project, and every time I learn more I end up getting excited and rewriting the project using my new knowledge. As such, JavaScript is the 3rd language it's been written in, you can see the [unworking] other my other repo.
Honestly, this is mostly for my own enjoyment. I've tried to fine-tune it and make it as detailed as possible, so feel free to play with it and have fun. But really this is just a hobby project, so if you're looking for actually useful software, this probably isn't what you're looking for.
To see more about this project, see my blog post about it here