I had some time on my hands recently, so I started doing a more detailed analysis of Kristin's pictures of the rainbow dress from the NYC runway show back in 2005. My observations pertain mostly to the underdress, and I welcome comments, corrections, or thoughts. I would especially love to hear from people with good draping/construction knowledge-- the fabric is definitely hanging in some interesting ways near the seams, and I know it's saying something about the grain and angle, but I don't know enough to decipher it.
According to Dressing a Galaxy, the dress is made of bias-cut silk chiffon and sanded charmeuse, or something to that effect. Whether the overdress is on the bias is a subject for another day, but I'm quite certain that these pictures confirm that the underdress is on the bias. At any rate, have a look-- you can clearly see that there are two triangular extensions on the bottom of the front panel, one on the left and one on the right. Green arrows indicate the regular vertical seam, red arrows indicate the angled extension seams:
I'm pretty sure those angled seams are what you get when you can't fit the whole bias panel on your width of fabric. Well, you'd get it on one side, anyway; I'm guessing they just mirrored it on the other side so it would look even. This also makes me think that the front panel of the dress is all one piece-- ie, there's no waist or empire seam. If there were, they should've been able to fit the whole panel on one width, and they wouldn't have needed extension pieces. However, there really are no good pictures of the bodice of the dress, because it's always covered by the overdress, so I can't say for sure.
There may also be a gore/godet/thingie inserted at each of the side seams, probably starting at the waist, which could account for the extreme fullness of the skirt. Check this seam out-- it's not the front panel seam seen above (you can see that seam on the right of the picture). It could also be the CB seam; the dress is rather swishy, and even just in these pictures, the seams move all over the place. The new seam is arrowed in blue; the other seams are green and red as before:
Assuming it is a gore, it looks to be quite large. In the next picture you can see a bit of the right front panel/gore seam, but nothing else:
Sadly, we can't really tell anything about the top of the dress, as it's always covered by the overdress. We *can* see that the model was a bit bigger than Natalie-- the dress rides higher in the back, and she's, er, kind of busting out of the top, so the bust and/or waist of the dress must be quite small and fitted:
There's also this still from one of the makings-of, which gives a little overall shape information:
That's pretty much all I've got for the underdress. So, my best guess for now is that it's a bias-cut dress with a front panel (and two front extensions), a back panel (likely split in two up the CB), and possibly two side gores.
Other random observations from the pictures-- you can see that the overdress doesn't actually close around the upper arm, and the outer edge of the binding doesn't close around the wrist (can't tell if the inner edge does):
Also, the overdress "sleeve" really does seem to have some structure to it-- maybe the gathers are stitched to some very light boning or something? If there's some sort of gauntlet or undersleeve there, it definitely doesn't go all the way up the arm:
And that's it! I hope it made at least some sense. Again, I welcome any comments, corrections, or general thoughts.