Adafruit has shared plenty of interesting DIY projects in the past. Their latest project shows you how to build a portable Raspberry Pi tablet using a 7″ touchscreen display, a Raspberry Pi 2 unit, a 2500 mAh battery, and an Adafruit PowerBoost 1000c. You are also going to need a 3D printed enclosure to fit all the components.
The above video highlights what this tablet is all about. You are going to need a 3D printer, screwdriver, soldering iron, and a few other tools to get started. Adafruit has shared a complete guide here.