I just finished the new chemisette I've been making and it's lovely! I made it with the blue gown in mind, so it has long sleeves and an actual bodice. I've made one chemisette before, but it's only this little ruffle collar-shirt front combination. The new one is much more substantial.
I drafted the pattern myself, using a normal shirt-front dress bodice pattern as guidelines. I made the back piece about 10cm shorter than the front and the back piece has a channel for a ribbon on its lower edge; the ribbon wraps around the front over the longer front piece and ties at the back. The sleeves are my standard sleeve pattern I've used for all the gowns, spencers and the pelisse; I only made them a little wider. I made the ruffle collar by gathering two 10cm x 140cm strips of the fabric on a cotton tape and then sewing it on the neckline. The idea is that it's easier to remove for when the chemisette needs to be washed.
The fabric I used is very thin silk, it was sold as "scarf silk" and it was very nice, if at times a little fiddly to work with. I made double seams to keep it from fraying and rolled all the edges very narrowly. I also sewed pintucks on the front and back of the bodice and on the cuffs to gather them.
Take a look of some pictures: