There's a few combined-process setups coming out these days that use 3D printing as a first pass and then machine the print in-place before sintering etc. which saves a ton of setup and fixturing time.
Yes! This is exactly what I had in mind. Sintering (thanks for the term) combined with this 3D printing technique could still make the process faster and lead to more consistent results.
Now that’s I think about it, one could in theory use the exact same process for plastic-polymer lenses too, albeit at lower temperatures (better).