Originally Posted by freecia

Just buy a few immersion heaters at once. They're inexpensive compared to a serious tea habit Maybe keep it in a brightly colored eyeglass/pencil case?

You can put an immersion heater in a titanium mug as long as the coil at the tip remains covered with liquid. I'd get the double walled mug, though, since the single walled mug can get pretty hot with hot water poured into it.