Our goal is to create a full functional plant, which processes 100% of all input types using the smallest possible area.
It is forbidden to build massively into the height.
Also it is forbidden to have massive clippings (meaning placing objects like storage, waterplant, smelters etc in a way they look placed inside each other. We can't avoid clippings at all to build so small, but at least try to keep it minimal.
Also let's say that all buildings should have "logical structural stability" - meaning that it's forbidden to build conveyors over a huge distance without ground support. Also it's forbidden to place Smelters hanging in the air.... - you get the gist i guess.

Ok - let's have fun:
First we need to prepare the area we want to build on.
I recommend to nuke a hole for the Big Hopper first, and place a rectangle 15 x 9 tiles.
It should look like this:
(Note: the 3 appending tiles are needed - the single one to attach the elevator, the double one will be used by parts of the last storage.

Then we want to place the 4 Big Hoppers, The 10x Speed Power Input, and the 2 Left turns at the outer end. Also we have to connect it to our main elevator.
Like this:

IMPORTANT:
Attach the Power Input to the pylon on the other side of the elevators (if you put all power to the same grid, it will explode (overpower). You need to do 2 different grids exactly as i did on the screenshots!

If you close the surface with Concrete Blocks, use Concrete Floor Tiles in front of the Elevator to avoid massive clippings:

After placing the 2 Elevators and the 4 WInd Turbines (each 2 Turbines per Power Grid) it should look like this:
That's all we need to be ready to start.

Let's build the main line (stone path) first:
Place Jaw Crusher, Shaker Screen, Coal Screen, Cone Crusher and Froth Floater - exactly in that order from top elevator down to ground.
It should now look like this:

That been done, we install the water pump for the Froth Floater:

And so our first part is already done.

Now we build our part for the seperated coal - see screenshot:
Put the Power Cable to the other grid (not the one we put the main power input (Hopper) on.

Once we are done with the coal path, we take care of our tailings after Froth Floater:
Use the second power grid!

Time to build a way to get our dirt and paydirt processed:
We first build some "weird" conveyor construct. This is necessary to get our Paydirt-Ore line as near as possible to our already existing "stone path" to save valuable space:
Attach power cable to the first power gid!

That been done, we can now place the Washplant and the Trommel. Don't forget the 2m piece between them, or the selling point will not match later:

Also our Washplant will get some water (not really necessary, but we have the space to fit it in):

If you did it right, there is now room where the Sellpoint matches perfectly underneath the Washplant, so that the Trommel drops the remaining Dirt automatically in there for auto-selling:

To make it look more realistic (structural integrity), you also can build a wall right underneath the Screen line:

At this point, we have 2 "ore lines". One from the Floather and another one from the Trommel.
To merge them without dropping directly on a conveyor or even use a Merger Conveyor, we have to use some "workarounds" (still within the "rules").
Don't worry - these concrete blocks do not hang in the air, they are supported from a column right behind them - you may see that on another screenshot angle:
(We use the second power grid for the Power Input)

This is quite straight forward.
Place them in that order to the conveyor like this:
(NOTE: if you want to produce Iron Bars instead of Steel Bars for whatever reason, simply swap them and place them in the other order)

We are nearly done!
We only need to place some conveyor belts, the Bar Roller and the last Storage.
Do not forget to put a 2m conveyor after the Bar Roller, or else there's a massive clipping to the Screener above!
It should now look like this:

DONE!
We squeezed the whole plant into a nearly 15 x 9 grid.
I hope you liked this guide - if yes, please leave a thumbs up XD
This is what it looks like overall from different angles after been finished:

And finally here is the full list of all items you have seen in this guide, including the Concrete Foundation, the Drop Zone Hopper and the whole Power Grid:

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