I designed this for my Mamba3D 3d-printer and it's done in OpenSCAD with all parameter defined up front, so you probably can modify this easily to something else. I wrote a blogpost on how i got this to work on my 3dprinter: http://www.oiepoie.nl/2015/09/19/auto-tramming-or-leveling-for-a-mamba3d-3dprinter/ The OpenSCAD program is a little messy, but i will put it up for download so anyone can adopt it to it's own needs. The design is driven by the goeal to make it a rigid product, so it doesn't vibrate much when the extruder moves to the measurement point for auto-tramming. I printed it with 30% honycomb infill. On the bottom there is a nice hex indent for the 12mm hex nut to fit into.http://www.oiepoie.nl/2015/09/19/auto-tramming-or-leveling-for-a-mamba3d-3dprinter/