Quantity   Component name
1 × 3mm Steel Rod (1-2 USD) This type of rods is often used for RC cars. These are used to create the two axis of the machine. You will need some sort of saw and sandpaper to cut them to the correct lengths.
1 × 28BYJ-48 Stepper motor and driver (less than 2 USD) The motor used to power the wheels. Be sure to take the version with a 1:64 reduction gear ratio for maximal torque, as 1:16 versions also exist.
2 × M3 10mm Screws and nuts To hold the motor in place