I recall seeing the technique used in the Amateur Scientist column in Scientific American, with epoxy or casting resin. The verdict was the result was "maybe f

I recall seeing the technique used in the Amateur Scientist column in Scientific American, with epoxy or casting resin. The verdict was the result was "maybe for infrared"... found it: https://optica.machorro.net/Optica/SciAm/LiquidMirror/1994-02-fs.html https://optica.machorro.net/Optica/SciAm/LiquidMirror/1994-0... If you search around, you'll find people have kept trying and have got somewhat better results in the meantime. Fun stuff.