I made my own version in fall colors, as shown above. The Koozie protects your fingers from the hot liquid, and also makes the tumbler look nicer and more personal.
You only need 12 squares of 2 1/2", backing and batting, and in addition some elastic and a button. Use the template included in the pattern.
This is a quick project to make, half an hour is all that is needed.
Here is the result, a lovely Coffee Koozie appropriate for the season!
There is even some coffee bean fabric on it.