Summary

This device mounts to a Frederiksen Air Track (sold by Pasco in the US) to provide a mounting hole to support an ultrasonic motion sensor. The provided pictures show the Vernier Go-Motion Sensor.

I should credit Roger Key with the original design. This is modified quite a bit from his design due to a new modification to the Frederiksen air track (circa 2017).

The central whole, horizontally is intended to be threaded. I drilled it out slightly and cut threads with a 6x1.0mm tap to match the mounting screw from Frederiksen.

This thing was made with Tinkercad. Edit it online https://www.tinkercad.com/things/cemwQBaP6r5