This is a derivative of Daids fanduct. I have integrated a mount for the Hall-O sensor and a place to put the magnet that was delivered with it. The magnet is held in place 4mm above the sensor field of the hall sensor. An approaching ferromagnetic build plate will change the field of the magnet. This gets detected by the hall sensor. A previous experiment has shown that the output signal changes over the range of approx. 0.3V. This change could be measured by the ardiuno, generating a repeatable indicator for the distance of printhead to bed. Thus enabling autoleveling.