Meet Opto: a cool VR headset with built-in audio that you can take anywhere to enjoy movies, games, and photos. It pairs with your smartphone to provide you with an immersive experience. Just remove the front cover, put in your phone, connect the audio, and put the front cover back on.
Opto works with 4 and 5.1 inch smartphones. With its magnetic cover, you can remove and add your phone easily. Yet another interesting VR project.