@soapone Aside the heat needed, you also need the proper minerals mix, and then proper furnace to let it cool down slowly.
Just like metals there are tons of configurations, but overall you can make some basic one with firebricks and some electric resistance.
Currently the technology of glass making is advanced enough to make it flexible, and also strong enough to make it as resistant enough for most plastic replacements. https://www.youtube.com/watch?v=vEvBpjCOBu0
@mangeurdenuage I'd like to melt glass down and do something interesting with it, but I'm really not sure what. Glass blowing is not something I've ever done and honestly have little interest in doing.
@mangeurdenuage I've been in the manufacturing (lathe and mill) industry for a very long time. Recently purchased a propane furnace to make sand and investment castings. It just makes me sad to see all those beer bottles go to waste. Not sure if that can be helped.