For the Jane Austen Evening last January, I wore a sleeveless spencer over a white dress. Due to several things not working out (fabrics, flu, knitting more than any one person should), I needed something relatively quick, which a sleeveless spencer is! I was mostly influenced by this painting and this fashion plate.
Construction information for this spencer can be found here. My shawl was a gift from a wonderful friend, and my fan is a lovely silver and white fan by Dengra Designs on Etsy. My necklace, earrings, and bracelets are by the incomparable Dames a la Mode, also on Etsy.
The spencer is lightweight silk taffetta from the Michael Levine's Home Store in the LA garment district lined with linen. It laces shut with ribbon from Farmhouse Fabrics. The dress is voile from Dharma Trading and just the bodice is lined in linen.
I'm wearing the dress over a shift from the Kanniks Korner pattern, stays based on the late 1790s/early 1800s stays in Corsets by Jill Salen made with cups instead of gussets, and a strapped petticoat.