For beer and wine bottles that tutorial looks brilliant!
I recall once seeing a WIP thread somewhere on the 'net where a guy made custom "glowey" chest plates for his Necrons by melting down fluorescent green styrene (chopped-up cocktail stirrers, IIRC) in a spoon, junkie-style, and cast it in a press mold he'd made.
I know you can also dissolve styrene in MEK (Testors liquid cement) to create a paste which re-hardens as the solvent evaporates out. I read about it like ten years ago as a way to putty gaps in plastic models, and tried it myself. As a putty it left something to be desired IMO, but there might be a way to pervert that into a casting method. Biggest thing I guess would be whether clear plastic handled that way would re-solidify clear or cloudy.