At our current state, we probably waste about a ring's worth of material to make a ring. The exact reason is because of our current compression molding systems, which lead to the use of hole saws and a wood lathe. Using a drill press with two sets of hole saws does create a semi- accurate blank for shaping on a lathe, but it does mean that we have to create more material than we use.
The only realistic way to fix this would be to create a new system of compression molding. This newer system would remove the need for hole saws. Considering our current molds are custom made at machine shops, these molds would be much more expensive to manufacture. Unless, of course, we were able to manufacture them ourselves. The answer to this is a Machine Lathe.
A Machine Lathe will allow us to directly manufacture our molds to very specific dimensions, including boring and honing the cylinders interior to fit a range of rings' outer dimensions. To fit the inner dimensions, we'll need rods in the center. As a result, the only 'wasted' material will be merely millimeters of material.
Of course, the greatest benefit of all this is speed. Not only will we reduce waste, but our entire system will be much more efficient, and save us an incredible amount of time.