Starting with some good quality veg tan. Local bovine, soft, not too thick (just under 2mm is fine), pretty much bag material. If you have a whole side, stay away from anything close to belly for this project
https://photos.smugmug.com/Other/Wor...ench-1-2-L.jpg
https://photos.smugmug.com/Other/Wor...ench-1-3-L.jpg