## 1 Introduction  
The digitisation of the product design and development process became established in the 1960s with the emergence of the first computer-aided design (CAD) systems. These enabled products to be modelled accurately, technical drawing tasks to be automated, and design documentation to be optimised. Although processing capacity was limited and the systems were expensive, their potential to increase accuracy, reduce errors, and speed up development cycles justified their gradual introduction. In the context of increasing digitalisation, immersive technologies such as virtual reality (VR) and augmented reality (AR) have emerged as tools with great potential [1, 2]. VR allows users to fully immerse themselves in simulated digital environments, offering highly realistic experiences that can be manipulated interactively [3, 4, 5]. And AR overlays digital information, such as 3D models, onto the perception of the real physical world, enriching existing reality [6, 7]. VR began to develop in the 1960s with pioneering devices such as the 'Sensorama' (1962) and 'The Sword of Damocles' (1968) [8]. Its evolution continued over the following decades, driven by organisations such as NASA [9; 10] and the United States Department of Defense [11; 12]. They promoted technologies such as data gloves [13], tracking systems [14], and computer-generated graphical environments [15]. In the 1990s, VR established itself as an interdisciplinary field with applications in design and engineering [16; 17]. The first generations of hardware were expensive, voluminous, heavy, low-resolution, and required additional hardware, limiting general interest and research in the early 2000s [18; 19]. In recent years, a new generation of much more affordable and accessible VR hardware has been developed. This has allowed the study of previously unfeasible applications [20; 21]. AR has also experienced notable growth, largely driven by the development of smartphones and their applications [22; 23]. The incorporation of VR and AR into industrial design has gradually evolved. Integration into the workflow is usually complemented by computer-aided design tools and additive manufacturing. Currently, immersive technologies are being integrated into all phases of the industrial design process [1; 24; 25]. They allow you to work directly in 3D environments, overcoming the limitations of traditional tools such as 2D sketches or traditional CAD [26; 27]. They facilitate 3D sketching [28; 29], immersive 3D modelling [30], rapid iteration of ideas [31; 32], product validation [33; 34], real-scale visualisation [35; 36] and integration with 3D printing [37]. They also improve creativity [32; 38], reduce time and costs [18], improve product quality [19], and enable more efficient remote collaboration [39; 40]. In this sense, immersive technologies represent a major contribution to the complete digitalisation of the design process. The application of immersive technologies has been led by large companies in the automotive and aerospace sectors. With the evolution of more affordable tools, their use has spread to academic settings, design studios, and small and medium enterprises [25; 41]. Several companies use immersive technologies to sketch and review concepts in 3D, optimising processes through simultaneous collaboration at different locations [42]; to apply AR and MR in their sales processes to improve customer experience through real-time customisation [43]; and to explore complex designs for 3D printing [44]. In recent years, increasing interest in immersive technologies has led to a large body of literature becoming available. More general studies have focused on the definition of technology and its evolution, components, and technical challenges.