I liked the LM8UU holders for my prusa mendel using this X-Carriage: http://www.thingiverse.com/thing:23897I decided to make one for the Rostock (build in progress).This is listed under work in progress until the Rostock is fully built.UPDATE 10-07-2012: My Rostock is "plotting" now. I discovered that my LM8UUs were sloppy on my drill rod so I doubled them up with this: http://www.thingiverse.com/thing:32000What I used in Slic3r: 0.35 nozzle. 0.20 layer height with 0.25 for the first layer. 45 deg fill at 40 percent fill using line method. No brim and no support material.This was done in 3mm ABS on my Prusa Mendel v2.Brims and support material is built into the model to prevent curling and support the brackets for the m3x20 and nut.To use the scad file, you will need the files from the github: https://github.com/jcrocholl/rostock and the scad from: http://www.thingiverse.com/thing:16158There are parameters to change the first layer height if it does not slice correctly. The STL is using 0.25 for the first layer.The LM8UU bearings should fit snugly in the holders without the bolts and should not require much torque to secure them well.