This is just the same robot as http://www.thingiverse.com/thing:18264But I've created a new part: spacers. Their objective is to support the Arduino board, allowing to place a 9V battery below it. Its advantage is that the battery is just above the wheels, so the grip is slightly increased :)The Arduino code which makes it able to navigate inside a corridor is also attached.Video of NS-1 working here: http://www.youtube.com/watch?v=xKkJGlzjeCMPrint and mount!Files attached: spacers.stl and spacers.scad and navigation.pde (Arduino code)The main chassis and wheels can be found here: http://www.thingiverse.com/thing:18264The scad has been generated using the OOML library ( http://iearobotics.com/oomlwiki/ ) but I don't share the OOML code because it is really really ugly. Anyway, if you want it just ask me.