Eli5: How are double walled glasses made?

Question

As an example, bodum makes coffee / tea glasses with an air space between two walls, insulating the drink, making it easy to hold the glass. How do they make it?

In: 3

Answer 1

One method is to make a tube with a sealed end, then wrap the open end back onto itself similarly to aluminum metal spinning. Like pulling off a sock from the top until it is half inside out. This is probably impossible by hand but a machine with the right tooling could do it.