I think the buckles would be metal therefor silver but the straps themselves would be a canvas of sorts....usually a brown or green
Found this link - s-media-cache-ak0.pinimg.com/.../c750ab9ea55f800174d0f4412b5fe58a.jpg
After painting the cockpit detail, put a gloss coat over everything and do a black or dark grey pinwash in areas like the tub's corners, in the seat's recesses ,under the pannel ect, when wipe the worst of just leaving enoug to give some shadow.
Theuns