Re-Worked Z Tops for Prusa i3 varient

I built these to replace [these z-axis tops](http://www.thingiverse.com/thing:118020). These should be much more resistant to flexing in the x-axis than the other ones.

These are based off of the tops for the reprap wallace but modified to fit 8mm or 5/16th rod that is commonly used on the prusa i3.

Enjoy.