I was using multiple gates as a test... None are really needed, just the Obsidian Pipe, it is self powering.That is an obsidian pipe so the drops can be sucked into the system. He looks to be using the Autarchic Gate function to power it instead of using an engine.
Yes the pit and water is 8x8, but if you don't have a wall on two sides you want 9x9 or the looni can spawn the stuff on the ledge.. Can't use hopperhock for this because it will collect the coal from the endoflames. The manapool MAY be able to be one further away, I didn't test as I liked this setup.