Stefan Vorkoetter, a hobbyist who messes about with all kinds of electronics and geeky stuff, from remote controlled airplanes to vintage sliderules, wanted a tablet that wasn’t constrained software-wise like many Android tablets seem to be. He was introduced to the Raspberry Pi and decided that it would make an excellent tablet device. He paired the Pi with the official touch screen and then added other components such as an Adafruit Powerboost 1000C, a 6200mAh LiPo battery, a real-time clock, the guts of a USB audio adapter and an amplifier board. He fashioned an absolutely gorgeous case for it out of wood and what I think is perspex and fit all the components carefully inside. He estimates between 4-12 hours of battery life, depending on usage and the whole thing comes in at 484g (just over 17oz). A truly wonderful tablet build which you can read more about, and see loads of build pictures, here.
