File Types

    When using MakerBot 3D printers and software, you may encounter types of files that are unfamiliar to you. STLS and OBJs are file types used for 3D models. THING files are a way of saving arrangements and settings for 3D models. GCode, .makerbot, X3G and S3G are toolpath files containing instructions for 3D printers.


    An STL is a widely-used type of 3D model file. It consists of surfaces made up of triangles. Each triangle has an inner side and an outer side. The outer side is called the “normal.” In a well-formed STL, all the normals face outward and the surface is continuous, with no holes. When a model meets these standards, it is referred to as “manifold.” STLs with normals that face inwards (inverted normals) may be printable, but manifold models are typically considered mandatory for 3D printing.

    STLs are compatible with many different 3D modeling programs and have become the standard file type for 3D printable models. SolidWorks®, Rhinoceros®, and most Autodesk® programs will export STL files, and there are free plugins available that will allow you to export STLs from SketchUp®.


    An OBJ is another type of 3D model file. It is also used by a number of 3D modeling programs, but is used for 3D printing less often than STL. Unlike STLs, where every facet of your 3D model is a triangle, an OBJ can contain both triangles and other polygons. Rhinoceros and some Autodesk programs will export OBJ files, but other programs, including SketchUp and SolidWorks, will require a plugin to export as OBJ.


    When you save a model or group of models in MakerBot Desktop, the default format for saving it will be a Thing file. A Thing file includes information about the orientation and position of each 3D model on the build plate. The file also allows you to include multiple models on the plate. When you save multiple models in a Thing file, you can continue to manipulate them individually. If you plate multiple models and save them in other formats, such as STL, you will no longer be able to move the individual models in relation to each other.

    The Thing format works only with MakerBot Desktop, so you should not save as Thing if you are saving a file for use with another program. If you have a Thing file and need to edit an individual STL file within it, change the file extension to .zip. Then unzip the file and extract the STL you need.


    .makerbot is the file type used to send instructions to Fifth Generation MakerBot 3D printers. If you are using a Fifth Generation MakerBot 3D printer, MakerBot Desktop automatically converts your file into the .makerbot format when sending it to a printer or saving it to your computer or to a USB drive. .makerbot files contain instructions for the print, such as extrusion temperatures and toolpaths. They also include additional information, such as thumbnail images of your model and details of the settings you used to slice it.

    GCode and X3G/S3G

    For MakerBot Replicator 3D printers prior to the Fifth Generation, the MakerBot Slicer turns your 3D model into a set of instructions using a computer language called GCode. The instructions consist of commands that tell the extruders how hot to get, where to move and when to start extruding plastic, commands that control the build platform, and commands for peripheral components, including the LEDs inside your MakerBot. For more information about GCode, click here.

    When exporting your print file, MakerBot Desktop automatically converts your human-readable GCode to a more compact, computer-readable format. For the MakerBot Replicator 2 and MakerBot Replicator 2X, and for Original MakerBot Replicators with firmware 7.0 or above, the correct format is X3G. For Original MakerBot Replicators with firmware below 7.0, the correct format is S3G.

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