A Babylon.js developer designs and implements graphic environments, games, and simulations using Babylon.js, a powerful engine based on WebGL/Web Audio APIs. They leverage the engine's features to create realistic physical behaviors, animations, and interactions within the virtual space. They integrate these visuals into websites, applications, or standalone experiences. The developer also optimizes performance, troubleshoots issues, and ensures compatibility across different platforms and devices. They may collaborate with other team members, such as designers or backend developers, to ensure the seamless integration of the elements into the overall project.