Researchers from Israel’s Technion Institute have discovered an innovative and comparably cheap, way to make optical lenses. It avoids the 80% waste of grinding and shaping glass slabs. A polymer is injected into a ring-shaped frame under water. Its benefits range from spectacles to telescopes.
https://israelbetweenthelines.com/2021/12/15/researchers-create-zero-waste-optical-lenses/