Prusa_i3_MK2_Z_Axis_Top_Bearing_688_2RS

Triggered by bibomator I decided to use 688_2RS bearings (https://www.amazon.com/Traxxas-8x16x5mm-Replacement-Precision-Bearings/dp/B00NKSA12G/ref=sr_1_3?ie=UTF8&qid=1489992724&sr=8-3&keywords=bearing+688) for Z axis top stabilization of my Prusa i3 Mk2.

In doing so I remixed Josef's initial Z axis top parts design.