2. A K'NEX Battery motor (any colour)
3. Four small K'NEX wheels such as the 90978 K'NEX Hub/Pulley Small plus 91975 K'NEX Tyre Small.
Then complete the whole base, adding an Interlocking clip Tan on each end of both axles, as shown.
Now would also be a good time to put 2 x AA batteries in your blue motor, if you have not already done so.
Now assemble the complete Battlebot, and test it by turning on the motor.
Please note that your own Battlebot does not have to look exactly like the one in our photo. Half the fun in building battlebots is making your own one unique!