In short, it's all about hiding the underlying infrastructure out of sight.
View attachment 12948
That's the section of Bloke Towers' machine wall that houses my main Mek processing setup. The pressurized tube with the blue stuff on the left is hydrogen chloride for the injecting factory, then there's a series of autoejects so it goes Inject->Purify->Crush->Enrich then up into the smelter. It's only 4x though. The 5x setup is too untidy and I have Rotarycraft extractors for that bit
The factory to the right of the smelter is the osmium compressor that isn't part of the system.
The underlying STUFF to make oxygen for the purifier and hydrogen chloride for the injector is in the basement, mostly:
View attachment 12949
You can just see (behind a pile of machinery) the the ExU drums that receive brine from my salination plants in the desert via tesseract. That pile of machines is two different setups, one extracting oxygen from water and the other working brine through two stages to make hydrogen chloride.