Printrbot Simple 1405 Bed Ends

Based on the awesome designs of @iamjonlawrence. I traced his ends in Autodesk Fusion 360 to extrude my own to support a custom bed laser cut from 1/4" MDF to match my 8x8 heated bed. This design is still a work in progress, I'm about 40mm shy from using the full 8x8 bed. Need to stretch the bed platform, and make some firmware that will allow for an offset to the G29 auto-level code.

Rev2 has yet to be printed, it has slightly larger nut captures since my first attempt tolerances were to