I printed the "Printrbot LC and LC+: Y Bearing Guide for GT2 32 teeth pulleys" by gyronictonic, and had to make a modification to the end as it hit the zip ties that are used to hold the Y-Bearings (picture of printed part is the original with the sanded end)
This derivative shortens the end so you do not need to sand it down. The center clearance for the pulley is also made larger to 15mm in the derivative.
Credit Where Credit is Due:
I have to say the original design is a great concept and give all the credit to Gyronictonic.