While I use CAD and CNC milling or hand carving wax models for casting for many of my designs, I also do old school fabrication from sheet and wire to create rings. Sometimes I use a combination of multiple techniques if it is the best solution for a particular design. I am not really married to one technique. I just use what is the most economical way to get a task done. I do enjoy traditional fabrication as much as incorporating new technologies. They are all just part of the process.
For mixed metal designs fabrication is usually the way to go especially if the shapes of each component is rather simple and does not require sculpting in wax. One great example would be designs like this sapphire and diamond engagement ring.
I did photograph the steps creating this ring from wire stock to show all the tasks that go into the making.