Now, I have been perplexed by the Thinness from the moment we first learned of it.

I believe I am satisfied with the idea of the Bore as a singularity that is like a hole through space-time. I like to think of the Pattern as a great folded sheet of paper suspended in the air over a good wooden floor (I promise I will explain).

Think of the thinness as a pin hole in the paper and the Dark One as a light bulb under the floor (outside of the pattern). Drilling the Bore was like poking a hole in the floor (maybe a gateway?) with the One Power and letting the light pour out. The light would fill the room but only pass through the pin hole into reality. So, only at the thinness could the Bore be sensed. Maybe thinking of this light as having liquid qualities would be more useful. This way one can understand the ripples of reality that occurred when a hole was made in the Prison. The pressure suddenly found some release leading to the rippling of the Pattern. Similarly, when in KOD the last of seals were presumably broken there was a second rippling (but this time the Bore was larger).

Why was it larger, you ask? Because we know from the Guide and elsewhere that the War of Power was begun when some Darkfriends, assumedly Ishamael and company, tried to free Shai'tan completely by widening the Bore. It is likely that there were ripple effects then too. When it happened in KOD it was a fully widened Bore so the ripples would be greater than when Mierin drilled through.

I think that because the Dark One could not do this on his own it suggests he would also be unable to hold open the Bore without human aid. Think about it. If he were inside the Bore, pushing through, then why would he be incapable of flexing himself and widening the Bore? Due to this evidence, I think the only explanation is that the Bore is similar to a gateway, or a drilling tube made of the One Power. A likely comparison would be drilling for oil. You don’t just poke a whole in the ground, you put a tube there so that it doesn’t just leak all over the place, and you leave the tube there (I am no expert on oil drilling, but I think this is the case).

As for the Sealing, it was like a Shield through the Bore. As the “shield” slid into place, however, it provided a small hole in the tube and the dark energy was able to leak out and race along the threads of power that were pushing the shield through. The seals, I believe were made of both saidin and saidar, but as they were tied off they did not provide any more access to the True Source than did the Bore weaves themselves. The One Hundred Companions, however, were placing the shield with direct weaves of saidin, allowing the Dark One the momentary opportunity to taint the male half of the True Source.

The actual Seal itself probably should be envisioned as a bubble, which blocks the Dark One from passing through the thinness and covers the Bore, rather than just a disc because of how the Forsaken were trapped. They were caught between the Bore and the Pattern, or maybe in the Bore itself. Ishamael must have been farthest from the thinness, and so was caught partially by the shield, if at all. Aginor and Balthamel must have been caught in the edge of the shield, so they were able to see, but ground against by time. The rest, however, were trapped in the Bore and outside of the Pattern, so I think it would be more likely that the shield extended over the Pit of Doom (the point of maximum thinness).

I contend that the Seals were incomplete because the True Power which Ishamael was surely channeling might have forced the One Power weaves to bend around that point, creating a hole. I say this because there was clearly a leak in the seals that seemed to follow some 40 or 1000 year pattern, depending on which Aes Sedai you ask. Also, the persistence of the Blight suggests that even in the best of times, the True Power was able to touch the world and corrupt it. When the Seanchan beat back the shadowspawn (creatures made from the True Power) from their Blight, the Blight disappeared. Also, and more importantly, when Rand slashed at Ishamael’s True Power connection in the Eye of The World (his big bulging black cord) and beat him then for the first time, the Blight receded hugely. I think it was no coincidence that reducing the amount of True Power in the world caused the Blight to grow smaller and weaker.

Ishamael’s connection to the TP at the time of the Sealing must have been like a foothold for himself and for the Dark One in this world. Note that the TP is drawn from the DO so it is like a part of the DO. Also note that Ishamael was able to use the TP immediately after the sealing (when he "heals" LTT). The TP should not have been useable or possible to sense if the Bore were closed or the DO truly cut off from the world. I believe that Asmodean’s partial shielding was very similar to what the weakening Seals are like for the Dark One and for Ishamael. The True Power kept and continued to keep the Seals from fully covering the thinness and the Bore, allowing the Dark One some access to the world and a chance to apply pressure to the Seals.

Now that we have laid out the nature of the Bore and the Seals, there still remains the problem of the Thinness. How can this make sense? Some at wotmania have suggested that channeling caused the thinness. This makes a little sense, but does not explain why the thinness exists ONLY at and around Shayol Ghul. People channeled in more places than at the Collam Daan. And besides, Shaylo Ghul (where the thinness was) and the Collam Daan were not in the same place. SG used to be an idyllic island in a cool sea, while the CD was in the heart of one of the great cities, V'saine. While it might be a stretch, I think the evidence points towards something that I have never seen discussed: the Thinness was a stedding in formation. The stedding are like places of healing for the Pattern. Working with the channeling-caused-the-thinness idea, the stedding act like band-aids that block out all of the power so that the Pattern can heal. Further, the beings that inhabit the stedding, the Ogier, are great healers of nature. The stedding must serve some purpose for the Pattern or else they would not exist in so many numbers. The Pattern is not perfect, and I surmise that it would develop thin spots over time through wear and tear (possibly from ta'veren, maybe from traveling). This is where the stedding and the Ogier would come in for repair. I am not suggesting that Ogier make stedding, but rather that whatever mechanism brought Ogier and stedding from their dimension to the human world may have been designed to reinforce or strengthen a Pattern woven through the creative, but nonetheless tension-laden relationship between saidar and saidin. Some have theorized that in the stedding, it is not so much that the OP doesn't exist as that the True Source is integrated, preventing both the tensions and the wondrous possibilities of a divided OP. Like platelets do for clotting in blood vessels, the stedding are environments that are more tranquil and provide places of healing. The Book of Translation likely translates the stedding to another dimension, and with them, all the weak points of the Pattern, leaving it stronger and whole.

Also, just as the stedding do not have reflections in Tel’aran’rhiod, neither do the Blight or Shayol Ghul. It is possible, however, that as stedding form, they disturb or thin TAR, which is what Mierin, a noted dreamwalker first detected. Perhaps the thinness was a mixing of reality and TAR that was kept from changing by the Bore. Thus, the DO's ability to manipulate reality around Shayol Ghul and its lack of TAR reflection. It has no reflection because it is neither real nor dream, but both. In effect, the Bore allowed the Dark One to create a sort of monster dark stedding. The Blight is the exact opposite of a stedding in many ways, but it also shares some similarities.

So, bringing it all together:
-The Bore is a tube of the One Power, it cannot be easily widened without the Bore completely able to be sensed.
-The Seals are a shield over or through the Bore and the thinness.
-Ishamael’s channeling of the True Power keeps any true healing process from happening and also acts as a foothold for the Dark One in this world.
-The Thinness was supposed to form into a stedding but Mierin sensed the Dark Energy first and stopped that natural process.
-To win the Last Battle Rand will have to clear away the Seals and then completely unravel the Bore tube, or maybe Sever the Dark One (unraveling vs. cutting weaves).
-Much of this battle may take place in TAR or with the aid of powerful dreamers like Egwene, Perrin and the wolves, and the Aiel dreamwalkers.
-Then the Ogier (and maybe the Dai'shain) need to be present to help the stedding naturally form over the weak spot in the Pattern. The presence of three ta’veren will make this great healing possible.
-The Book of Translation will be opened several years later (or maybe not that long) and take all the stedding into another dimension, and with them, the weakened spots of the Pattern.
-Thus when the wheel turns again, and the Pattern has more problems, the Ogier will reappear with the stedding (the first age?) and the dark one’s prison will be whole.