Dual 608 bearing Y idler for Prusa i3 with 10mm threaded rod

Remix of http://www.thingiverse.com/thing:222794

-Increased the diameter of the threaded bolt support to 10mm.
-Increased the length of the idler. Shorter version added.
-Slightly increased the hex nut and bolt cavities.
-Slightly reduced the bearing rim.

You will need:
1x M8x30mm Cap screw
1x M8 nut
2x 608 bearings
2x M4x20mm Cap screws
2x M4 nuts