However, I will be putting in a 1.3" OLED display so I can visually see the percentage of the value of the Potentiometers. That has 4 pins. But, again, inside the aluminum enclosure project box. Being in the box (which I heard metal creates kinda like a Faraday Cage, you still think I would need to put a filter circuit on it? If I put resistors/capacitor filter on the Potentiometers, it will change my values, but I guess I can just adjust that with the multiplier i have in the program to compensate. There really isn't much going on with this circuit, and the guy in the video did not add anything to his circuit, and it was working very well for him. I want to do it right, but if it isn't needed, no sense to.
Yes, the metal enclosure helps a lot. Consider a closed, continuous (welded, say) box, with one hole for one wire to come through. Nothing's getting through the box, the only place noise can enter is along the wire, along with whatever signal/power is on it. Filter this signal with respect to ground (which is the enclosure), where the wire passes through it, and you have clean signals inside.
Now consider if we open up a hole in the box. If no wires go through it, then it's only radio signals that can pass, and high frequencies at that (corresponding to the size of the hole). Still fairly good shielding, even if it's looking like Swiss cheese, and as long as we've got signals filtered with respect to ground.
Now consider more wires going into the box. If we filter each one with respect to ground (the box), they're all treated the same, and everything stays clean on the inside.
Now for practicalities. Suppose we route the wires onto a PCB, because that's easier to do than filtering right on the enclosure itself. Now we're asking the PCB to act as part of the enclosure, but it has to be mounted somewhere inside the enclosure, not actually as the enclosure itself*.
We need the next best ground then, which is going to be some screws and standoffs mounting the board inside the enclosure, and providing a ground connection that way. Say we put two ground screws on one edge of the board, and the connectors and filters are all placed on the board on that same side. That keeps the noise off to that side of the board, and the internal signals are surrounded by ground (ground plane and enclosure) and relatively free from interference.
*Well, you could actually arrange it that way, and it would be pretty good if you can work out the electrical details -- I mean, install the PCB over a hole in the enclosure, one side exposed to the world, one side facing in, and with a ground plane which carries the same ground as the enclosure, so the connectors can be filtered directly to ground as such.
I think it's best to think about shielding in terms of the ideal case (full shield), made worse by certain geometric transformations -- opening holes in the walls, terminating or filtering potentially-noisy wires with respect to the walls, or if not the walls directly, then the next closest thing, without opening up loops between the wires and the walls. (Example, a board that's grounded on the opposite end of where the connectors are, would carry noise through the board, making a huge loop under the board. That's not so great.)
You can also continue this stripping process, all the way down to a bare board. Then you have only the ground plane for ground-as-such, and traces and components are fairly open and exposed to noise, but that's still not necessarily a terrible thing as long as the signals (with respect to local ground plane) are clean enough for purpose. Noise is not so much one wire with respect to an ideal, absolute ground, as one wire with respect to all the others; but as it happens, this doesn't force a change in topology, as we can at least contain those (noise) currents to one side of the board, and have all the active circuitry off to one side, away from all the connectors (which are grouped on the other side).
For your case, building with dev boards, you're probably going to add a "glue" board, on which you can place connectors and filters and stuff, and which gets grounded to the enclosure. Short cables or headers then connect to the dev boards, which therefore stay clean, away from the noisy outside world. If you need very little "glue" (basically just the filters, no, like, I/O transceivers or voltage regulators or whatever), you may get away with using the main dev board in this way, minding to tie ground to the enclosure in an opportune spot (don't be afraid to scratch away soldermask and make your own ground pads if needed -- it's your board, you can modify it however you like!).
Or if using the dev boards just for circuit reference, and basically copying all that onto a single main board proper -- same idea, connectors and grounds to one side, everything else on the other side.
Tim