This adaptor allows you to use 10mm rods with Igus JSM-1012-10 bushings, and fits in the space intended for an LM8LUU bearing.
The HyperCube Evolution provides an XY Joiner for 10mm X rods, but the X carriage only accepts LM8LUU bearings, there is no official 10mm version of the X carriage.
This would allow you to use the original HyperCube Evolution X carriage and use carbon fibre or aluminium rod or tube on the X axis, or just allows to not use a noisy metal linear bearing on a 10mm steel rod.
OpenSCAD source is included.
This will be a tight press fit, so make sure you have calibrated your extrusion multiplier properly: http://print.theporto.com/posts/how-to-calibrate-extrusion-thickness/
I recommend you do a test print of say 10mm high first, and then test the inner and outer diameter and scale accordingly.
For me, this size prints as a perfect press fit for the bushings, and within 0.01mm the size of an actual LM8LUU.