Step 1: Get the Parts
2 555 timers (You only need one but get two just in case you break one.)
Jumper Wires/ Component Leads
General Purpose NPN transistor (don't use a power transistor...it requires more power to operate.) (2N3904,BC547, etc.)
Servo Motor (DON' T use a micro servo...no torque...) (Use a continuous rotation servo if not...mod a regular servo.)
Batteries and accompanying holders
SPDT Slide Switch (don't use rocker or toggle)
Step 2: Build the circuit.
Get the accompanying horns that come with the servo and pick the one with TWO arms.
Unscrew the old horn and replace the new one...if you already have it in well then...GREAT!
Once the switch is soldered and the motor is mounted test it out... if it starts rotating one way then flip the switch...if it works...
Now hot glue the slide switch to the motor. Make sure that if its going on the right side of the servo with the horn on its left the 68Kohm resistor is closest to the end of the servo.
If its on the left follow the exact opposite.
OIL the SLIDE SWITCH!!!