My main design goal was to have good ergonomics. This design fits nicely with my large hands, with an analog joystick that I find more comfortable than a D-pad, and large illuminated buttons with nice mechanical action instead of small membrane buttons.
The mechanical assembly is fairly simple, only two printed pieces, with nearly all the electrical parts attached to the front half. It has an internal battery charger, and can be played while charging - although you will discharge faster than you charge, so you still need to shut down to recharge fully. The second USB port on the PI is accessible, so you can plug in a USB drive to transfer roms, or an external keyboard for configuration or emulating systems needing a keyboard.If you want to make this for yourself, you can download the files and print them out for free by visiting his Thingaverse page.