"sweat equity" is as cheap as you are willing to work
... after reading the article, spherical lenses are great in many many applications, there is still a place for aspheric optics one of which is large aperture telescopes you can reach without an orchard ladder or drone.
the sibling comment on spinning fluids does lead the question; can the researchers vary the density of their neutral fluid (or polymer) to gradually vary the "local" forces shaping the lens
Sounds like you could cure the polymer while the container is spinning...
The original idea (polymer lenses) is definitely a huge potential for amateur astronomes making large refracting telescopes.
At the end of the article they mention being able to make large mirrors with liquid metal using the same technique as for the lenses. I do not quite understand how this is supposed to work.
