I hadn't actually thought of using the wire rollers. I suppose I assumed I would have to crank them down to the final size. I wouldn't actually mind if they ended up with a slight bezel either.
James, I'd seen the ebay cheapo ones but because they don't always have the sizes marked I wasn't sure about getting one. The one's I've seen with the sizes marked didn't match the sizes I needed. I'll have a go though. I use quite a bit of wire anyway so it would be a useful bit of kit.
Dennis, it's a fair point about using the draw plate for that size of wire. I'd be tempted to enlist my neighbour's son since I don't have a draw bench. And yes, making them from just one gauge of wire would make life easier, but trust me, there actually is a difference between the two when wearing them. The 6mm is much heavier and not entirely comfortable for smaller necks. I was actually thinking of making the thicker ones much thicker, maybe 8mm because I sometimes think that on larger necks, 6mm looks a bit puny.
I have a bit of 6mm length, so I might give it a go and see.
Thanks for all the suggestions.