Usually you make a case FOR your Raspberry Pi, but software developed by Walter Schreppers enables you to print WITH your Raspberry Pi. In addition to acting as printer controller, it enables you to control it remotely via web interface. Next developments will include support for web camera. Github page states that it works with Ultimaker, RepRap, Makerbot ... check it out ...
https://github.com/w-A-L-L-e/printerface
https://github.com/w-A-L-L-e/printerface
