From now on, your favorite designs will be on your mug. By this simple lid design, you can find your favorite prints in thingiverse and add them on your lid. For custom design, you just need to measure your mug"s mouth dimension and scale the base_mug_lid part accordingly. Then add your favorite design on top of it. That's all! This mug lid is also functional. It will keep your drink warm in cold weather and prevent spills. (might need an o-ring for better performance).