I had a single peice collar/backplate that I sold recently, it didn't look to bad and fitted snug. I didn't make it though but from what I could suss out the piece had to be split and re-joined down the middle of the back. Any ways heres a pic
Yeah, Jango's collar and backplate don't even touch, so that's not an issue. As for Boba's, I wouldn't want them to be one solid piece for safety reasons. I can just see my backplate getting snagged on something and the collar piece choking me. At least with the two piece configuration, there's more flexibility for it, and if the tension gets to be too much, the parts will break apart, rather than break my neck. That's just me though.