Styrofoam Cup Holder

This is a little something I created so that I wouldn't turn over my coffee while working. It's contoured to the shape of the cup on the inside for a better fit. I have noticed that when I have a full cup of coffee, the cup grips the sides of the holder. When I am down to approximately 2/3 of a cup, it no longer does. You may want to up-size a few percent, or sand the inside smooth. I think the cups are 12 ounces at my job. (They have 12CI8 on the underside.) I also added (taped) a small