Clip the (16 mm) shaft of your caliper to the rails of your Printrbot Plus to get some serious bed leveling action! Clip your caliper into the slot, and hang the unit on the x carriage rails. Zero the caliper at a corner of the print bed and read the measurements as you move the unit around to get some sweet accuracy. (or is it precision?)Print object on end with no support. Recommended to print with a brim on the base (2 perimeters or so) for added strength during printing.