Ice smooth WALL?E cake sides and background areas. Use tip 3 to outline and fill in gray eye sockets. Use tip 4 to outline and fill in pupil (smooth with finger dipped in cornstarch). Add tip 3 dot highlight. Use tip 8 to outline tire treads in black; fill in with dark gray (smooth with finger). Outline and fill in tire gears with tip 5 (smooth with finger). Outline and fill in smooth area of control box with tip 4 (smooth with finger). Outline remaining details with tip 4; cover with tip 16 stars. For vent, pipe tip 1 lines and tip 3 dot. For smooth control box area, add tip 1 lines and tip 16 star. Pipe tip 8 connector cord. Pipe "WALL?" with tip 2; outline and fill in circle then overpipe tip 1 "E." Add tip 21 star bottom border. Position cake on covered board.