The concept is easy enough to follow: find sand, melt the crap out of it at over 1093 degrees Celsius, and then watch sand turn into glass. But when you want to do something with that molten glass like say, make a glass bottle, it gets so much harder. You have to juggle so many skills at once — spinning! blowing! heating! — and employ all types of tricks to get even a semblance of a bottle and not some droopy glob mess.
Our favourite YouTube channel of the moment — How to Make Everything — shows a normal guy trying to learn how to make a glass bottle and makes you realise how skilled the experts are and how uh, not skilled most humans are at this.