Cassidy has a very good write-up about the origin and fundamentals of the robe a Lévite, which you can read here. I also have a Pinterest board that’s dedicated to trying to identify portraits of women wearing the Lévite, as opposed to the fashion plates. The Lévite is one of those weird 18th century fashions that, if you believe the sheer number of them in fashion-plate form, was apparently hugely popular– however, there seem to be precious few portraits painted of women wearing them, and even fewer extant examples (according to my source, there *might* be one in an undisclosed collection in Europe, but she was unable to view it to confirm).
In other words, there’s not much known about how this style of gown was constructed, other than what can be sussed out from fashion plate images. It could have had either a seamed waist, meaning the bodice and skirt were two separate pieces stitched together, or a partially seamed waist (which is how I constructed mine — the back piece is separate from the skirt, but the fronts are cut in one, and have a bit of a tuck at the waist to fit the torso better). The main elements of the levite, which distinguishes it from the Turque (its close cousin) is it has long sleeves that reach to the wrist, with turn-back cuffs, as opposed to short sleeves with an undersleeve/separate bodice. The collar tended to be wider overall, and, this is the clincher, there was always a sash worn with it. The sash seems to be integral to the definition of the Lévite.
There’s evidence that this was a more relaxed style, and that women could opt to go without stays while wearing it. Certainly this uncorseted look is present in this particular portrait:
Also, there’s this portrait of a woman nursing, which also appears to be a Lévite:
I chose to wear mine over stays, which is just my preference, since I don’t always like the “casual” look on myself.
What I did like about this outfit was its versatility. I re-wore it a number of times in France, doing little things differently with it. One night I wore it over my chemise a la reine, which turned out to be rather flattering! When I attempt another Lévite I will play around with a different method of construction, since I was pretty much flying blind while patterning it. There’s not a lot of issues with the construction, but I think the next time around I’ll have a better idea of what I’m doing overall and it will make for a better gown. Still, I’m quite happy with it!