Imagine you’re sculpting your own shapes in a vast, empty 3D space. So far, we’ve created rectangles, boxes spheres, torus, but what if you want complete control over your geometry? What if you want to build something unique—a shape that Three.js doesn’t provide out of the box? Welcome to custom geometries ! In this lesson, we’ll dive into the core of 3D modeling by manually defining a triangle using vertices. This is where we start thinking like 3D artists and engineers. Sample image ### **Understanding Custom Geometry **