[mabarker1]

The cups are built with a double wall and the space between them has a vacuum. This functions like a double pane window in the thermal aspect. 180°F beverage inside and outside will be ambient.

I knew a Scientific Glass Blower that made one of these back in the late sixties early seventies for His personal use. His was made from glass. In the scientific world it's called a Dewar's Flask

He wrapped the outside of His with Adhesive Tape for a better grip.

[wbarmy]

I use the Thermos Stainless King Vacuum Insulated Stainless Steel Mug, 16oz, Matte Army Green which does not leak even when turned over. Best travel mug I have ever had. Tours in AFG, IRQ and Africa and it is still going. The paint job is a little rough though, has taken quite a beating.

[RainMan]

So basically this. https://www.seattlecoffeegear.com/bodum-bistro-double-wall-coffee-mugs-10-or-15-ounces?sku=ACU861A0060

[HeadOn]

Thanks for the memory! 58 years ago in my first grade world, we called it a “Thermos”, and there was one in everyone’s metal lunchbox. But don’t drop it! When a Thermos rattles, it’s no good any more.