Duplicator i3 Filament Stand

I wanted a replacement stand for the Wanhao Duplicator i3 that would allow the spool to rotate smoothly so the extruder would not jerk the spool. I also wanted it to mount using the two existing screw locations and accomodate any size spool.

This is my second try at a the spool stand, the first version had a problem with the top of the inside supports hitting the filament when the spool was full. This new version hopefully fixes that problem. I also changed the design so that it now prints in three parts; a base and two sliders. The base mounts in the stock location on top of the printer and the two sliders slide onto the base. The spool rolls on four u-shaped bearings (guide wire bearings). The sliders have a hole for a m4 screw to lock the slider in position on the base, locking down one slider is sufficient since the deep u-shape of the bearings will keep the other slider in place. The only difference between the two sliders is the location of this hole.

The bearings are