In fact, this is a Z Endstop Trigger for the 3 Points Leveling for Makerbot Replicator... (http://www.thingiverse.com/thing:106474 )
Together with the thing mentioned above, it makes it very easy to switch between different thickness of glasses or not glass at all or this tape or the other...
...once the platform is level, just choose the build surface you'd like to use and adjust the endstop trigger accordinly, no need to level anything again!
The OpenSCAD scripts I used are not available for download, the reason is that I'm using a new library for nuts'n'bolts which is still under development and has too much details to polish. Sorry for that.
I suspect there's no gonna be much need for this thing, that's why I give it such a name. The Screw and the Nut are a nice thing to print and may have other uses.