Just thought I'd throw in my own two cents (or currency of your choice), especially regarding those silver strips/gaps on the corridor panels. I've spent way too many hours staring at them!
We don't get many examples of viewing the gaps head on, but
Charlie X and
LTBYLB both have a nice view down the straight corridor outside the Transporter Room, showing the gaps on the inner corridor wall.
Charlie X also gives us a rare straight on(ish) look at the silver strips on the outer wall - if there is any difference in width between the inner and outer strips, it is tiny.
And here's that silver material looking rather dented in ATCSL!
Using the adjacent wall panels as a guide, it is clear that the silver strips are 1½" wide - although this might initially seem a curious figure, I think it was used because it is a whole fraction of 1 foot and feet is what the sets were measured out in. So a grouping of two 2-foot panels, two 3-foot panels and a 4-foot panel (plus 4 silver strips) would equal exactly 14'6"
It just makes for much easier maths when deciding which panels to allocate to the circumference of a circle!
I drew all Season One and Season Two corridor configurations a couple of years ago in Inkscape (because it is vector based) and the 1½" system works extremely well, because at no point do you end up with odd distances like 7'4" or 14'5", it's always nice fractions of feet.
I started using 1" (scaled of course) in my model, but have come to question it. I think Robert has a diagram somewhere that says 1.5"? Anyway, one thing to keep in mind is that for the curved corridor, you will likely end up with different widths on the inboard vs. outboard walls because one is convex while the other is concave. I think Desilu made some compromises because of this, and I've noticed that we don't clearly see the joints on the inboard side as much as we do those on the outboard side.
I don't have the answer, but the more I work on the physical model, the more I find myself thinking in terms of the materials that would have been available to Desilu. I suspect this gap is based on the width of a 2x4, which would be 1.5". The question is, would they have shaved one side on an angle, as the T&T plans suggest, or would they have just abutted the two adjoining panels right up against the 2x4 and rotated them a few degrees to get the needed angle? (An angle which I have measured on the Babel plan to generally vary from about 2 to 7 degrees in the curved corridor, since the panel widths vary a lot.)
If it was the latter, then the gaps will be narrower than 1.5" on the outboard side and wider than 1.5" on the inboard side. I'm guessing they used standard 2" foil tape along the 2x4's edge and just folded it around the corners, so this could have worked out all right in either method.
The width difference of the gaps between the inner and outer position on the corridor panels is not as great as you might expect, thanks in part to the generous 51' radius of the outer wall (later Trek series sets had much tighter radii).
When you're dealing with width differences of between one-twelfth and one-tenth of an inch, that's quite a bit of wiggle room!
On the above example I have assumed that the wall panels are 1½" deep, since that's how far the silver strips seems to be set back. Everything else is still speculation!
Clues to the construction of the gaps can be gleaned from this pic of the "Environmental Engineering" alcove partially dismantled. It appears that each wall panel had a small jam sticking out of the side, which would probably butt up against the adjacent wall panel, before a silver strip was applied to cover the join.
No doubt braces were added behind the wall panels to hold them firmly together.
