Bearing holder for Prusa MK2 carriage and Bear Upgrade

Bear upgrade bearing holders are designed for prusa MK3s/MK2.5 carriage, leaving a gap where they might twist and skew bed out of alignment, causing bed skew for older bed designs.

This mode is redesign of the bearings in openscad, where the bearing holder is extended by 2mm so it covers the bearing completely holding them in place, and use M4 bolts which seem to be popular with older bed carriage deigns.

This mod uses nopSCADlib. If you wanted to modify the designs, you need to have openscad with nopSCADlib installed on your system.