Once again I'm ashamed of my lack of Dremel skills. The product of a feverish desire to take the Sega Dreamcast out on the move, this mod is a custom vacuum casing containing not only the guts of the console but a set of two 7.2V 3Ah R/C car batteries. Rather intimidatingly, the game CD simply clips onto the spindle at the back with no door or cover to protect your soft, delicate fingers.
A small LCD screen, all the controls you'd normally find on a Dreamcast controller (albeit with no viewing hatch for the plug-in memory block/mini-game that made the console so cool) and stereo speakers round out the hardware. Sadly, if you want one of your own, you'll have to make it yourself!