To make sure that my ring sizing is correct I order a plastic 3D printed version of the piece. If the plastic piece fits my clients finger then I know the sterling silver will fit perfectly.
Here's the high-res plastic version of my skull ring with split mandible. It was printed through www.shapeways.com where I have posted quite a few of my designs.
The test size fits great so the sterling silver is ordered and in production. It should be done by early February.