Hi my name is Bob from Australia I'm new to this site. I do a lot of braiding (we call it plaiting down here). When it comes too rounding leather and you haven't got a rounder go to a tool shop and get a copper pipe flaring tool around $15:00. The tool has 6-8 holes of different sizes. Ideal for this type of job. Just put it in a vice and wet your leather and pull it back and forth. When I get some time I will upload some photo's.
Happy Plaiting