Additive manufacturing ('3D printing') has already proven to be a revolutionary technology in industries as diverse as medicine, architecture, industrial design and aerospace. At the same time affordable consumer-grade printers have put 3d printing increasingly within reach of the general public. However the user interfaces of most 3D printers still leave something to be desired. Interaction is generally performed via a monochrome LCD and jog dial. Network connectivity is often an afterthought with file transfers primarily performed via SD Card. OpenGB is an Open Source 3D printer control interface. It was developed in conjunction with re:3D as part of the Open Gigabot project but was designed to work on a variety of Open Source 3D printers. In this talk James Stewart will describe the OpenGB backend which is written in Python and acts as an intermediary between the network and the printer. Various technologies are employed including: Tornado, Websockets, JSONRPC, Multiprocessing & pySerial. As well as 3D printing enthusiasts, this talk will be of interest to anybody using Python to control a lower-level controller such as Arduino.