I am looking for writings/tutorials/videos which describe a specific technology or feature by implementing them, ideally in no more than few thousands lines of code (and not just 10-20 line code snippets). Idea is to teach about underlying technology by a hands-on project, which is not overwhelming like trying to implement full-feature game engine and yet captures the essence of technology. Some examples are –
* Build a simple database (https://cstack.github.io/db_tutorial/)

* Containers in 500 lines (https://blog.lizzie.io/linux-containers-in-500-loc.html)

* Malloc tutorial (https://danluu.com/malloc-tutorial/)

* Nativecoin – build your own crypto-currency (https://lhartikk.github.io/)

I’m sure there are great such projects/tutorials in domains like networking, filesystem, databases, compiler, web design, messaging, game design, fintech, etc. If you have come across such writings/projects, kindly share.