Vapor honing. Very easy, as shown, beautiful results. Also used alot in awards casting and cabinet industry. Also flame honing.
It should not be done, ever.
Vapor honing of acrylic and polycarbonate actually starts the destruction of the material.
As the chemist described earlier, the acetone vapor depolymerizes and then repolymerizes the material. So now a TLDR on polymers:
all molded plastics have internal stress induced from the rapid freeze cycle after melt injection. This is why, for example, all plastics warp. There is a type of photography that shows color spectrum of internal stress in plastics, it's quite illuminating.
vapor honing depolymerize -repolymerize cycle develops stress different to the base part, but huge stress in the affected layer.
because vapor honing is usually done as shown, hand held and unevenly, the new internal stresses develop unevenly.
in optically clear polymers, internal stress over time leads to crazing: micro cracks that eventually grow to so many the material turns cloudy. The difficulty, and why people such as craftsmen, reject this advice, is the application unevenness leads to unequal time for crazing to occur, as well as severity. I have seen both acrylic and PC vapor honed and craze into deep internal cracks within days as well as years.
So, vapor and flame honing are OK if you're making a photography or short term display model. If your part has optical performance or aesthetic display purpose for months or years, vapor and flame honing should not be used. The only long term stable optical polishing method is previously described: multi level buffing with chemically compatible compound for the plastic.
tl;dr Ја уништува пластиката.