3D challenge coins have gained popularity due to their ability to provide a more realistic and visually striking representation of a design. 3D elements create a sense of depth and dimension, making the coin more visually appealing and memorable.  This allows for intricate designs and detailed features that can't be achieved with traditional 2D methods.  You can create unique shapes, textures, and even moving parts within the design.  The added complexity and visual impact of 3D coins often convey a higher perceived value, making them ideal for special occasions or as gifts.