It is very hard to make a great coffee mug. It needs to be made of pottery (clay, ceramic, stoneware, porcelain, earthenware). This will help it keep the coffee hot and not be too hot to hold. It needs to be big enough to hold the amount of coffee the person likes to drink in one sitting. Too big and it will get cold. Too small and there is not enough. Too large and it is not comfortable to hold either. Too small can be the same. Let's follow me for more information.