I would just call tack shack or quillins and ask them to make you one if you just want the chain.
Mine is Tack Shack and the sleeve is a lovely, super thin, soft leather, but I noticed the last time I was in there, the ones hanging up were a bit thicker cut. Maybe because the old kind wore out a bit faster? Anyway, I’m sure if you talk to them they will let you know all the details, they are super good that way.
Hre’s a close up. This is what it looks like when you look down from ponying and realize the little shit has been hanging on to th epony horse rein for who knows how long (he wasn’t chewing or pulling, just holding it)