1. A hobby gearmotor
2. A battery box with switch that holds two AAA batteries
3. 2xAAA batteries

Orient the holder so that the hole for the battery box switch is facing towards you.

Press the motor into the holder with the cables facing to the left side (this will make it so that the monkey's arms will rotate forward rather than backwards when turned on with the switch facing you.

The motor has two cables that we'll need to wire to the battery box. To ensure that the wires do not get tangled when the motor is spinning, we'll first thread the cables through a retaining ring built into the holder.

Thread the wires through the retaining ring one-by-one.

add the battery box without the batteries inside just yet Insert the battery box into the holder from the bottom, threading the battery wires through the hole on the side of the holder.

Make sure that the battery box is inserted such that the switch is accessible through the opening in the holder.

Press fit each of the arms onto the motor spindle, orienting each arm 180 degrees from the other. If you find the fit between the arms and motor spindle to be loose, you can add a thin piece of tape to the motor spindle to close the gap.

Turn on the switch. Your monkey should now be doing pinwheels.