3D TVs did not exactly become as popular as some experts expected them to. That does not mean people are not interested in watching 3D content. Expensive equipment and content have been an issue for consumers. The Sanwa 3D View-Master is a cool gadget you can use to watch 3D YouTube videos on your iPhone. This little gadget sends videos in side by side format to each eye. It fits your iPhone 4 and 4S. You can adjust the volume by using the hole at the bottom. It will cost around $25.