Roller Coasters Simulation
Companies that make roller coasters use simulators to design their roller coasters. This is much easier than testing the designs out in real life, because they can make changes very quickly. Also, their simulators are more accurate than doing tests, which makes them less likely to make dangerous tracks.
Construction of anything from cars to kitchens uses 3D models to design what they're going to build before they build it. This is a much quicker, cheaper way of designing things. Car companies can also use the 3D models in programming, so that computer-operated machines can make the cars.