I had an old Sparkfun 20x4 serial enabled LCD lying around and I decided to make it work for my Printrbot Simple. My version was older and has the serial backpack soldered to it. If you get a new one from Sparkfun, you don't need the box sticking out the back, as the serial circuit is built in. This is being driven by a custom script on my Raspberry Pi, which is running Repetier-Server. New LCD here: https://www.sparkfun.com/products/9568