PrintrBot Simple 14"x6" (360mm x 160mm) Bed

Replace two parts in [X-axis extension thing 215294](http://www.thingiverse.com/thing:215294) to make use of the increased Y-axis travel of the [Y-axis extension thing 229854](http://www.thingiverse.com/thing:229854). Includes built-in bed-leveling adjustment - without springs! (see instructions for details)