Hi Colin,

I'm flattered that you milled my signet ring (or one that looks like it)...;-)

I might be overly frugal about wasting wax, but I can see that you give the model
a margin of extra material to support it in the wax blank, using the cone system.

When I mill rings right off a hollow tube, I can space them a few millimeters apart
and just run a wax blade between them to slice off each ring as it's done, and then core out the finger hole.
I leave a few mm of material on each side, which serves as a guideline to the finger size.
I have a tool similar to the Matt Reamer, but prefer to use a large barrel burr. Some people also use a lathe.

Aside from using the extra wax, the cone system looks like it works pretty well.
I may mill some cone shaped clamps out of some nylon I have here and improvise a system like that for small rings
In the past, if a ring's inside diameter is smaller that a size 4.5 (smaller the opening of the hollow wax tubes)
I've used a bold, lock washers and nuts from the hardware store to fixture solid cylinders of
wax in the 4th-axis clamp of my Model Master mill. It's also possible to cut some three sided rings straight off
the 4th axis clamp without needing to use special fixtures. Here's an example-
http://tinyurl.com/yp8bvx/yp8bvx/yp8bvx/yp8bvx
http://tinyurl.com/2du7g8/2du7g8/2du7g8/2du7g8
Jesse