interface with the machine / process / system, which could be enabled by incorporating digital twin technology. Business firms Mixed reality allows sellers to show the customers how a certain commodity will suit their demands. A seller may demonstrate how a certain product will fit into the homes of the buyer. The buyer with the assistance of the VR can virtually pick the item, spin around and place to their desired points. This improves the buyer’s confidence of making a purchase and reduces the number of returns. Architectural firms can allow customers to virtually visit their desired homes. Display technologies and Products While Mixed Reality refers to the intertwining of the virtual world and the physical world at a high level, there are a variety of digital mediums used to accomplish a mixed reality environment. They may range from handheld devices to entire rooms, each having practical uses in different disciplines. Cave Automatic Virtual Environment The Cave Automatic Virtual Environment (CAVE) is an environment, typically a small room located in a larger outer room, in which a user is surrounded by projected displays around them, above them, and below them. 3D glasses and surround sound complement the projections to provide the user with a sense of perspective that aims to simulate the physical world. Since being developed, CAVE systems have been adopted by engineers developing and testing prototype products. They allow product designers to test their prototypes before expending resources to produce a physical prototype, while also opening doors for "hands-on" testing on non-tangible objects such as microscopic environments or entire factory floors. After developing the CAVE, the same researchers eventually released the CAVE2, which builds off of the original CAVE's shortcomings. The original projections were substituted for 37 megapixel 3D LCD panels, network cables integrate the CAVE2 with the internet, and a more precise camera system allows the environment to shift as the user moves throughout it. Head-up display Head-up display (HUD) is a display that projects imagery directly in front of a viewer without heavily obfuscating their environment. A standard HUD is composed of three elements: a projector, which is responsible for overlaying the graphics of the HUD, the combiner, which is the surface the graphics are projected onto, and the computer, which integrates the two other components and computes any real-time calculations or adjustments. Prototype HUDs were first used in military applications to aid fighter pilots in