this is the front sensor mount. for the inmoov robot left hand.

move info at http://thehackettfamily.org/blog/

print settings
30% infill
.2mm slice

Sensor: Hall Effect ratiometric a1302 sensors
Rare Earth Neodymium Magnet 8mm x 5mm
Spring size is 3/8" x 3/4"

update 29/5/13:
uploaded circuit diagram.