My stays are based on these 1790s stays in the Kent State University Museum. They're perfect for use under transitional 1790s dresses which have a high waist, defined bust and are full in front. Not only does the short length of the stays not give the stomach control so desirable under flatter dresses from the early 1800s, but they actually push your stomach out a little (mine at least, but something I've noticed with other short corsets) which full skirts cover quite nicely.
On the left, you can see the pink linen closed drawers I made to wear under my late 1790s/early 1800s riding habit.
Please excuse the state of the hotel room in the background. It was Costume College! Pretty standard mess for that :)
Except for the cups, which are one layer of cotton sateen, the stays are made with three layers of fabric. They're entirely handsewn. I basically used 18th century techniques, and flatlined the main layers and then attached a separate lining. The outer layer is cotton sateen, the inner layer is linen canvas and the lining is cotton batiste. I boned them using reed, except at the center front where I used spring steel.
The side of the corset. And a good view of the underam gusset on my chemise as well :)