Outreach & Education is an essential part of High Energy Physics (HEP) experiments where visualisation is one of the key factor. 3D visualisation and advanced VR (Virtual Reality), AR (Augmented Reality), and MR (Mixed Reality) extensions make it possible to visualise detectors’ facilities, explain their purpose, and functionalities, and visualise different physical events together with essential parameters. The visualisation applications should be extensive, easily accessible, compatible with most hardware and operating systems, simple in use, and with a well-developed user framework and open source. The best fit to these requirements brings browser-based applications based on the gaming engines. However, it causes limitations in the performance because codes are interpreted in real-time by the browsers and all data should be downloaded from the servers. Geometry descriptions play a critical role in finding agreement between the browser-based applications' performance and the quality of the visualization scene. Best cognitive results are delivered by so-called ‘as-built’ geometry descriptions. However, ‘as-built’ geometry is complex and consists of a decade of millions of primitives, parts and large assemblies. Therefore, bringing them into one visualization scene is almost impossible due to the engine’s limitations. The paper describes the TRACER framework and 3D scene development methods for AR/VR applications.