You're asking a potter....
On the last few trips I've been carrying a stoneware mug by a Japanese potter whose work I like. It was a gift to me from a Japanese ceramics student of mine. Yes, it's clay. No it's not UL. No, it's not practical by most people's standards.
But coffee is more enjoyable in it. Everything is more enjoyable when consumed from a nice piece of clay.
Certain objects are mere objects. Others are an expression of an idea, of a personality, a sentiment held when they were made. When I drink out of a cup made by an artist I admire, I think of that person, of how their hands shaped the work, of where they were when they made it. I'm drinking with them, in a sense. If it was a gift, I can think of the person who gave it to me. I like being connected to people and objects in this way.
I will often rotate cups/bowls made by other artists with my own. I have to use and enjoy my own work as well. Certain cups pass the test, others don't.
For a while I was also carrying the Mysterious Kupilka that showed up on my doorstep one day. A kind, anonymous person sent it to me as a gift. I still have fun using that cup; it has a history, a life, a bit of a story.
I encourage everyone to bring a little art into their life; function is not everything.