The vest is black twill, many yards of twill tape, and a couple buckles and D-rings (ok, 16 D-rings). I kind of had a pattern, meaning I used a scan from gosurori vol. 3 (the vest/jacket shown on the cover) and a blouse pattern. I don't actually have the magazine, so I adapted a commercial blouse pattern... no mockup, just drew the shapes right on the fabric.
It's pretty hard to see the details since it's all black on black, so I'll try to explain. The points on the front, armholes, and bottoms of the tails are all bound with twill tape. The buckles along the spine are also twill tape but it had the buckles already attached. I bought this trim at one point because I thought it was cool, without a specific project in mind, so I'm glad I remembered it and could use it.
Oh man, this collar. I drew it mostly free-hand onto some paper using the picture/measurements in the magazine scan. I'm a little surprised it didn't cause me much trouble. It was originally too long for the neck opening in the vest, but I just cut the opening slightly larger and it works.
There's several different ways the straps on the front can be tied off (or not). They kind of give the vest a bit of a straight jacket vibe, which I am definitely a fan of.
Above, you can see the side straps (undone here). These help keep the back of the vest close to the body since it's weight is pretty unbalanced.
In case you're curious, this is what the tails look like flat. The scan had them even wider but I could only get this much width out of my piece of fabric.
Since the vest is unlined, I covered every seam that's visible while it's worn with twill tape (seen in the images above and below).
I'm pretty happy with how this all came out, especially considering I didn't really have a pattern and had a limited amount of fabric that was less than suggested by the magazine scan. There's some places where things don't quite line up (that's what I get for not planning where I'll put straps before sewing all the fabric pieces together). Still, it's one of those projects where I finish and think "holy hell I actually made this... how did I make this?"