I plan to use this on my Mini Kossel delta printer instead of the existing shower roller carriages. They fit perfectly and have zero play in them. They do not wrap all the way around the 15mm extrusion because I am using the back side of the aluminum extrusion to hide the end stop wiring and I have printed wire covers. youtube video to show how they should work: https://www.youtube.com/watch?v=hfuVoxgvb8U Update: I redesigned this and made it a bit better in the anti-twist department. The extended legs resist twisting. Installed and working well! If you can get this to print with Nylon, it might be slightly better than PLA. Another observation Ive had after a few hours of use, one of the bushings I printed had a little too much play in it, so when the printer would move side to side on the Z axis, the bushing would twist, and that causes the print head to tilt, and thats no bueno. However, I have been printing at .15mm the Robotica and it is printing incredibly fine detail. Robotica: http://www.thingiverse.com/thing:614366 I printed these using a .5mm nozzle, using PLA at 210 degrees hotend (e3dv6) and 55 degrees bed temp. The layer height is .3 mm