KAKURI Leather Corner Punch Tool 9mm Made in Japan, Professional Leather Cutter Knife Half-Round U Gouge, Sharp Japanese Carbon Steel Blade

Your corners look really good (actually the whole product does). Mine, not so much, so I picked this up: https://www.amazon.com/dp/B091P2F47Y But I just took a guess at the corner radius. I picked up some scrap leather while traveling, but I'd like to find leather that is of the same or near properties as the stuff TRC uses.