I've done my share of tsukamaki (although it's been almost entirely on knives, not swords) using synthetic material. In my opinion, it is not particularly difficult but requires a lot of patience and attention to detail. I have never used leather, but I have heard that it is far more likely to stretch over time than other materials unless you stabilize it with epoxy or lacquer etc.
There are some excellent videos on youtube that will help you out. Wally Hayes has a couple of great videos out, each with a good section on mostly-traditional tsukamaki. Walter Sorrells has an excellent video on traditionally mounting japanese blades that covers tsukamaki in detail.
- Chris
