In a nutshell, glass is the main insulator of glass and its insulating properties, as well as its hardness, can be used to insulate objects from the cold.
The key to making a good insulator is to select glass materials that have a high water-resistance and a low thermal conductivity, which means the insulating qualities will decrease as they cool.
Glass is a relatively inexpensive insulator because its properties can be easily adjusted to make it suitable for certain applications.
Glass can also be made to be thinner and lighter, which will make it more durable.
The best way to make glass is to buy glass from a reputable glass supplier, as it is the only material that can withstand a wide variety of temperature changes and the most expensive.