hypercube: mgn12 Z axis

replacing those lm8uu bearing with those "china" MGN12.
sliced and diced with cura
needs supports " touching build plate"
35% infill
layer height .3
The rail clamp has two option to bolt down the rail with the slot allows a bolt though rail and bracket.
Endstop mount clamping bolt hole "at the rear" needs a round file going though it!! its a little under size for m3.

mk3 been added, require 10 mm bolts and no supports necessary again you still need a round file for the holes!.