If you own an iPad, you also own a fully-functioning 3D scanner — provided you buy yourself a Structure Sensor ($380). This little device comes with a bracket made to fit on the back of your iPad, right on top of the built-in camera. It connects to your iPad using a Lightning cable, and can alternatively connect to just about any other device with a USB cable. Using the sensor and your iPad, you can measure the three-dimensional space in any room, automatically capture three-dimensional models of everyday objects, and even simulate physics on top of the real world. If you're hacking inclined, you can use their SDK to develop iOS apps for it, or even take it a step further by connecting it to other devices.