Had a stroke of luck recently: the robe isn't lined (or if it is, it doesn't make any visible difference)! It's not really noticeable on screen and I only caught it going through screencaps, but the finished edge of the sleeve is visible on the inside.
Which means I don't have to bother with a lining. All I'll need is extra fabric for the faux lining that sticks out from under the edges, but I'll just use scraps of the same outer fabric. So the time and cost of this project (or at least this portion of it) just got cut in half. Hurrah!
After (finally) buying the movie on Blu-Ray and watching it again, I've realized that the nightgown is a lot more sheer than I had remembered. Which means the habotai I was considering before is a really good idea again. Without a lining the cost is also feasible again, and I think it'll be a really good match for movement and sheen. So I'm still thinking about options, but I'll probably go with the polyester habotai as the best for both cost and screen-match. I've also decided on a particular silver charmeuse satin for the robe.
Meanwhile, LOTS of visible progress over the past few weeks.
Most recently I did a mock-up of Lucille's braid. As far as I can tell - which is hard to tell, just like most details in that scene - it's not a standard braid but more knotted and twisted and wrapped.
I mostly followed
this tutorial, just added an extra hair tie at the very top to keep everything secured and left a large strand of hair out of the loops, splitting that strand in two and wrapping it in opposite directions around each hair tie after the loops were done. I might play with it some more (probably add some more smaller, separate wrapped strands), but all in all it turned out close enough and looks really cool anyway.
Mock-ups are where the real progress has been made.
The nightgown started out as McCall's 6743, which had the gathered scooped neck, raglan sleeves (or the right shape to add them in), and a lot of fullness through the body. I used view A and extended the hem to the floor. For the pleats I planned to use
a historical German hemd tutorial, which calls for two 55-56" bodice pieces and two 28" sleeves. That's where the extra width in the earlier sleeve modification came from, bringing the sleeve up from 3" to about 28-30." To add the extra width to the body I made a second center piece (the original pattern uses two sides and one center per front and back) and then extended each pattern piece about 4" so each total front and back would be about 55". I also added about an inch to the height of the neckline, intending to fold that under to finish the edge and create the slight ruffle above the pleating, but it ended up being unnecessary so I'll take that back out when I do the final. The maths on lengthening the whole thing failed me, so it ended up a few inches too long, but better that than too short. I scrapped the idea of testing the pleats themselves, so I just did a few rows of gathering to get an idea. It turned out well, so it'll be a good fallback if for any reason the pleats don't work.
I did another mock-up of the sleeve with the extra width. Instead of tapering that width down to the wrist like I'd planned, I left it the same width all the way down so I could easily cut it on the fold. And because, you know, there's no such thing as too much with Lucille's impractical clothes apparently, so why not make the wrist more full.
The robe started as Simplicity 1551, view B. I started with the back and side back, cutting and sewing those together to make one big piece. I also adjusted the seam lines to get rid of the fitted princess seams while retaining fullness. Rather than cut the robe back with the pattern, the whole back will be draped from the full width of one piece of 60" fabric with the center being pleated by hand (similar to a robe à la française or Watteau pleats for you historical costumers) and the new pattern piece traced on the edges for the flat and unpleated sides, sleeve head, and the train. It's hard to get a good look at it in the movie, and I think there's more to it than this, but this is pretty close. Also, draping pleats is the funnest thing ever.
Using the pattern again for the front of the robe, I followed the same process as the back, getting rid of the princess seams and turning the two pieces into one large piece. This way, each front and back is only one piece, and there's only a side seam on the final thing. I widened the shoulder and collar area so it's less of a v-neck like the pattern shows, and matched this extra width along the collar of the back piece. The sleeve heads took a lot of fiddling with, both because I had changed some seam lines and it needed to be enlarged to accommodate the size of the nightgown's armhole and sleeve bulk. As a result, the sleeve itself was a total nightmare. Which was ironically fitting, since the robe sleeve was supposed to be the one piece that was perfect as-is. I'm not even sure what all I did to it or how I finally got it to work, but basically I lowered the bottom (armpit) of the sleeve to match the new armhole shape, and widened the top (shoulder) of the sleeve to allow more pleats and give a better overlap of the edges. There's still some wonky bits along the underarm, but nothing really problematic, so I'm happy enough with it.
So all together, it actually looks like a proper thing now!
I'm calling the mock-ups done at this point, since there are only a few little tweaks. So as soon as I make some final decisions, I'll be ordering fabric (and maybe a wig).