Linear Bearing Carriage X Axis LMB6UU NOT LM8UU as I originally put hereI found some LMB6UU (SW06UU in US) linear bearings for £4.50 each, so tried them as a direct replacement for the bushes on the Y Axis based on thing http://www.thingiverse.com/thing:9114 by splod, they worked so well that I created an X Axis carriage for them and here it is if anyone would like to try it.

People in the UK can get them from http://www.worldofcnc.com/products.asp?recnumber=167 or get them from eBay ALOT cheaper

Update:I printed the ABP version and found a miscalculation in the end bolt holes; these are corrected in the _FIXED versions of the STL and SCAD files