One of the best ways to learn more about electronics is by building your own gadgets. Adafruit has put together a guide that shows you how to build your own 7″ multitouch tablet powered by a Raspberry Pi. They used a Raspberry Pi 2, a 7″ touchscreen display, an Adafruit PowerBoost 1000c, and a 2500mAh battery to get the job done. The enclosure that fits all the components is 3D printed.
The above video gives you a better idea how to build your own Raspberry Pi tablet.