An additional servo motor is never a bad idea! The set also includes an RGB module.
You can build these robots with the extension baton light finder scanner
Contents: - 1x RGB LED module - 1x 9g servo - 1x servo arm - 1x servo motor driver - 2x rectangle plate 3*7hole - 1x flat beam-15holes - 1x screw M2.5* 5 - 10x screw M4*15 - 2x lock screw M4*5 - 4x plastic spacer 7*4*3 - 1x RJ11 cable 180mm - 1x rectangle plate 3*9hole - 1x 9g servo L-bracket - 1x L-bracket 3*6 hole - 4x screw M2*8 - 20x screw M4*9 - 20x nut M4*3 - 1x wrench - 1x RJ11 cable 120mm