Printrbot Simple Maker's Kit Version 3 (1403) Large Build Plate Upgrade Extension

After upgrading to jamjonlawrence's x-upgrade and 300mm y-axis no sag upgrade I installed a large glass build plate of 350mm X 300mm. The glass build plate was hanging and thus it was very difficult to level the build plate evenly. So, I designed this extension to provide support for the build plate. I have not printed it myself yet. Will provide detailed instructions and pictures after I am done printing and assembling it.