And I love the idea very much indeed. It’s chilly and rather 
than getting up and brewing a fresh glass every time or reheating the pot, I’m gladly using the Thermos! And as I just discovered on Wikipedia, were it not for a patenting issue, it might’ve been called a Dewar flask instead!
And a cooler idea was the tea infusion ball. I just boil the water, fill up the infusion ball with lemongrass, drop the ball into the thermos and pour boiling water on top! Here’s a photo of my thermos and a warm cup of lemongrass tea with the new cam.