FolgerTech 2020 Y Axis Idler Bearing Holder

I didn't like Folgertech's Y-axis idler pulley design for their 2020 i3 printer. It was fiddly to assemble the bearings, washers and angle brackets, and the resulting assembly carried the belt a couple of mm higher than the motor pinion. So I designed this.

Required:
* M5 X 25 hex-head bolt
* M5 Nylock nut and washer
* 2 5 x 10 x 4 *flanged* ball bearings

Installation:
* Wrap the belt around the two flanged bearings, with the flanges on the outside to act as belt guides
* Run the bolt