We have all seen the nice and shiny Cases so I'm going to show only things I don't have seen so much (or never).
I never understood why you want to have the SD Card in the cardridge, cause when you have ALL Roms, you have them all, no need to reach the SD Card easily...And in case of trouble there's ssh. But What to do with the now empty Cardrige? What do you need most on a mobile gaming station? Right! Batteries. So I put in some good old fashioned Samsung Galaxy S1 (I9000) Lion Batteries (which you can get with up to 2900mah). I Also wanted to know how much juice is left in the battery while gaming, So I grabbed a nice small MAX17043 and a WS2812b RGB LED an soldered it to the Arduino Pro Micro I'm using. Cause thats what Arduinos can do best, measure stuff

[spoiler="See Pictures"] [/spoiler]