X3G

X3G is a binary file format used to convey 3D printer instructions to certain fused deposition modeling (FDM) printers, most notably those in MakerBot’s early ecosystems. It encodes a sequence of printer commands that govern movements, extrusion, temperature settings, fan control, and dwell times, enabling a model to be produced layer by layer. Unlike plain G-code, which is text-based, X3G packages the commands in a compact binary form that is consumed by the printer firmware or by the software stack that prepares a print job.

X3G files are typically generated by MakerBot’s printing software or by converters that translate standard G-code into the X3G stream. In its niche, the format is associated with MakerBot Replicator and related devices; several open-source tools and libraries provide support for parsing or producing X3G, enabling workflows that involve conversion to or from G-code for interoperability.

The structure of an X3G file consists of a sequence of discrete records, each representing a printer action such as a movement, an extrusion event, a temperature change, or a pause. Each record encodes parameters including coordinates, extrusion length, feed rate, and tool state. Because the format has historically been tied to proprietary firmware, exact encoding and supported command sets can vary between printer models and firmware revisions.

In contemporary practice, X3G has largely been superseded by standard G-code workflows on many printers. However, the format remains of historical importance within MakerBot’s early hardware and in legacy or niche workflows that require access to X3G files. Tools and libraries exist to convert between X3G and G-code, aiding interoperability across printer platforms.