I've been dreaming of making a mod like this for a while, but never could figure out which combo of hidden entities and fluid boxes could make it work. You managed that, and even included a convenient UI and tutorial for them. Thanks for doing the hard work, and sharing it with the rest of us plebeians.

Thanks for the kind words! I really appreciate it. It was a fun challenge to code, and still have a few ideas. But it's only working because of new API additions in Factorio 2.0 that makes it possible, so wasn't really possible before :)