To be honest, the couplers aren't coming on .............. yet, am trying to find somewhere to buy them, only thing then is that there are already established places that sell perfectly good quality ones, and probably as cheap as I could, am thinking that it might be best to stick to what I know ...........
Not trying to be an arse, just mean that where I can add individuality to collar design, it looks like couplers are couplers, I can't see what I can add to them to make them better/different, but am certainly open to suggestion mate!
All the best.