MakerBot Print is our newest print-prepration software, which supports native CAD files and STL assemblies,
allows you to interact with all your printers via the Cloud, and many other exciting new features.
I was thinking to bearings too, but I gave up because it was too complicated and it should have too much mechanical slack.
I tried on a 3d model with an alternative of your Z parts divided in two to create a pivot with threated rods. If i'm stuck with it I'll let you know but I guess it will work :) Just need to work a little bit on those alternative Z parts.