Two mounts, left right for the original printrbot to hold a 2 mm glas or Polycarbonat.
I print on Polycarbonat. When the part is cold, I can take the PC with the part from the bed. Easily you can take the part from the PC.
The front: http://www.thingiverse.com/thing:53682
Easy to assemble, look at the picture. I took a 3 mm screw to fix the glas / PC. For the screw I made a 3 mm thread in the ABS. It works.If you take screws to fix the glass or PC look out that they do not collied with the printing head !