This Lego Mindstorms EV3 robot's "Tortoise" body accommodates a top "Shell" that can be quickly attached. In FIRST Lego League (FLL), valuable time can be saved by having attachments quickly pop onto (and off of) the robot (less time wasted --> more missions done --> more points). The shell's arms rotate via the Power Take-Off (PTO) gears on the EV3 Large Motor heads. Be sure to keep the EV3 Programmable Brick's screen and buttons clear, so that they can be easily seen during the FLL robot game. Large Lego Motorcycle wheels+tires ( www.bricklink.com/catalogItemInv.asp?P=51378c01 ) save space, increase travel speed, and improve grip. There are two EV3 Color Sensors and an EV3 Gyro Sensor inside the bumpers. Go to the "MOC Details" page noted above to see how a gear "ladder" in the shell assembly allows for multiple locations for the green Technic Liftarm to be attached. The Lego Digital Designer (LDD) .lxf Building Instructions file is for the Base+Shell is available on Bricksafe: www.bricksafe.com/files/dluders/EV3%20Tortoise%20Base%20w... . Experiment and design your own shell!