The second picture shows a closeup with the Arduino Pro Micro, the Sensor Board, Power Switch and Output Jack.

The Sensor board is attached to the "front" of the case with Hot-Glue so it's fixed in relation to the case.

The third picture shows the distance sensor chip (the two greenish "windows") in all its splendor.

The next picture shows a small loudspeaker that was carefully removed and cut from the plastic framework surrounding it.

This is one of the most "advanced" features of our project: the user feels timed pulses indicating the distance to the nearest object.

Most other similar products (even commercial) use a simple vibrator that just spins a motor with an ex-centric weight.  While varying the voltage on such a vibrator does vary the level of vibration, those "levels of vibration" are much less repeatable and distinguishable than our precisely timed pulses.