DoomMeister's, Kuehlings Sells/Prusa X Ends

I am busy renovating/improving my sells Mendel to use linear bearings, smaller pitch belts and proper lead-screws and I noticed a few things.

1. Prusa (iteration 2) X ends don't fit the sells design, the distance between the Z axis and lead-screw is 30mm not 29mm. I only noticed this after printing a set :(. As an aside I think the belt driven Z lead-screw is a much better design than the dual motor one and will be sticking with it.
2. There are a great many x axis designs for trapezoidal (ACME) lead screws, but they all use metal nuts. As evidenced by my old Z screws, and the small pile of iron fillings at the bottom of the Z screws on my Orca this is not a good idea.
3. The Prusa SCAD sources are a pain in the bum to edit.

With this in mind I have modified Jonas Kuehlings - Improved X ends for Prusa with clamped rods
to accept a plastic lead-screw nut which you can machine or print. The Z nut press fits into the holder (use an 8mm bolt to help) and is held in place with a key bolt.

I have split the Z Nut into another thing as I prefer to GPL my things and base for this design is CC-BY-SA

Files posted for both the Sells and Prusa Mendel.