Sorry I forgot to write anything at first!
A LBD made of my own pattern (though based on a free Lekala pattern, the modifications were so extensive it's really my own now). The fabric, ribbed, is mostly rayon, with some stretch but also enough body for the skirt to hold the shape nicely.
My favourite feature, though, is the V-neckline in the back and the shaped sleeve hems. And topstitched facings.
The jacket I'm wearing it with is a 70s thing I got from my friend's mother, with buttons that my grandfather made.
And the sleeve!