I know there is a black Gi worn the jacket. You can see it on close ups. if your good at sow and just get a pattern that fits you and then some vinyl for the "leather piece"
Until the release of the movie, and we may or may not see Kylo with out the surcoat. It is hard to see what it looks like. So this is just my take on it based on some concept art and what others have noted from seeing the display in person. Also this is the most difficult and time consuming...