I hope this will someday describe how to detect the print bed level on a Solidoodle using a FSR (force sensitive resistor). At the moment, this is just a little part I printed to anchor the wires from the resistor to provide strain relief and keep the resistor from moving. It is screwed on with the extruder fan, and replaces the stack of washers that come with the Solidoodle. It also has a hook for the other end of the spring that goes with http://www.thingiverse.com/thing:214112.

Lots of details on the evolution and progress of this thing can be found at: http://home.comcast.net/~tomhorsley/hardware/solidoodle/solidoodle-bedlevel.html