In the past few months, we have covered plenty of awesome Arduino and Raspberry Pi projects. The folks at adafruit.com have put up a video that shows you how to build your own portable gaming device powered by the Raspberry Pi. You are going to need a Raspberry Pi A+, a PiTFT 2.4″ 320x240 touch display, a speaker, a 2000 mAh battery, tactile buttons, and a few other parts to get started.
You are also going to need a 3D printer to make custom enclosures when trying projects like this. The good news is all the parts and instructions are available on adafruit.com, so you can get started faster.