Double Vertical carriage for Rostock with Kühling's LM8UU holder

My LM8UUs were sloppy on the drill rod so rather than trying to find another set of linear bearings with less slop, I just doubled them up.

With them in a pair on each rod, they have very little backlash (if not none).

I'm using Kühling's (awesome) holders again, but the ones he designed for the X prusa ends.