Ben Krasnow also did a good piece on this, showing a system that he built with a 4F correlator. Of course, his piece is full of things that look like things you could build at home if you had infinite resources on hand ... but it really does drive home just how possible it is to build this system, and provides a very intuitive view of how it works.

His piece is: https://www.youtube.com/watch?v=wcRB3TWIAXE