Well, I finally finished that corset, and figured I'd share the photos!
I started with a muslin corset pattern I made a while back for a previous corset (I've made a few.) I like to draft my own patterns, but there are lots of good commercially available patterns on the internet that will be much, much easier to deal with. Because my weight varies a bit, I decided to have it lace both front and back so it would be more adjustable. The side seams end up pulling too far to the front if you only have it back lace. This isn't a problem if we're talking ten pounds, but at twenty, well, then you have a box of "skinny corsets" and a box of "fat corsets" unless some are front and back lacing. The front flap with the inset hides the front lacing, and closes using buckles and straps.
I used the left over leather from my "steampunk leather top hat," https://www.instructables.com/id/Leather-Steampunk-Top-Hat/
It was a "utility hide" from Tandy. Now you know as much as I do about the type of leather I used. I sewed it on a Viking Iris/Rose, which is a high quality home sewing machine. It only was really angry at me when I sewed over 5 layers or more. I purchased all the leather tools and leather notions from Tandy over the years.