Collect a sensor, two three-hole grey pieces, and a double-length black connector unit.
Correction: The double-length black connector piece should go into the LAST hole of the three-hole grey piece. Step 15 will not be possible otherwise.
Connect the three pieces above as shown. Note that the double-length black connector piece goes into the middle hole of the sensor.
Connect the two sensors built earlier to the previously assembled sensor. Also, collect a black bar and two slim grey holder pieces.
Connect the sensors with the black bar and attach the slim grey holder pieces at either end.
Connect the sensor apparatus to the piece finished in step 9. Note that this piece will be wobbly for the moment.
Collect the piece created in step 7 and attach it as shown. (Yes, we realize we said to make it unnecessarily early...) This will help to stabilize the sensor array and keep it from wobbling so much.
Collect the pieces depicted below.
Attach the pieces as shown. This provides further stability to the sensor array, keeping it essentially stationary under normal operating conditions.
