To build the immersive LEGO world, we used Three.js to create an endless LEGO plate, locking the camera to keep participants centered. We used 3D models of iconic LEGO bricks that could be customized with colors, drawings, and text, with the UI coded in Vue.js. Here, we programmed 2D gestures on smartphones to control 3D movement, allowing participants to "place" bricks and even "sense" when they stack atop one another.