Exporting 3D Files for Molding and 3D Printing

exporting 3d files for molding and 3d printing


Properly preparing a 3D CAD file is an important step in order to ensure your design data is the best it can be before sending to an injection molder or 3D printer.

3D CAD part files are created using design software such as SolidWorks, CATIA or Autodesk.  The “native” design files are proprietary to the particular software maker and can’t be easily read by other software packages used to design molds or print parts.  Therefore, “neutral” files must be created and exported.

3D Files for Molding

The most common neutral file format typically used for injection mold tool design is STEP (.stp).  It is our top preference as well, but we can also use IGES (.igs) if necessary.  Make sure to export as a solid and not surfaces.

3D Files for Printing

The defacto standard neutral file format for 3D printing is Stereolithography (.stl).  3D printer prep (slicer) software typically imports an STL file, applies printer and slicer settings as specified by the user, and then exports a GCODE file which is loaded into the printer in order to create the part.

This STL format basically approximates the surfaces of a solid model with triangles.  The more complex a part becomes, the more triangles are required to duplicate the part model.  And as a result, the more triangles, the larger the STL file.  For most parts, STL files larger than 5MB are not necessary.  Therefore, it is important to ensure the export options in your design software are properly tuned in order to get an accurate file without creating an enormous file.  Below are general guidelines and suggestions for creating STL files depending on which design software is being used:

(Credit for STL saving instructions goes to 3D Systems)


  • Your design must be a three-dimensional solid object to output an STL file.

  • Make sure the model is in positive space 

  • Set Facetres to 10 

  • At the command prompt type STLOUT 

  • Select Objects 

  • Choose Y for Binary 

  • Choose Filename 

CadKey / KeyCreator

  • Choose Stereolithography from Export options

  • Enter the filename 

  • Click OK 

Geomagic Design (former Alibre)

  • File

  • Export 

  • Save As >STL 

  • Enter File Name 

  • Save 


  • File >Export >Rapid Prototype File >OK

  • Select the Part to be Prototyped 

  • Select Prototype Device >SLA500.dat >OK 

  • Set absolute facet deviation to 0.000395 

  • Select Binary >OK 


  • Save Copy As

  • Select STL 

  • Choose Options >Set to High 

  • Enter File Name 

  • Save 


  • Right Click on the part

  • Part Properties >Rendering 

  • Set Facet Surface Smoothing to 150 

  • File >Export 

  • Choose .STL 

Mechanical Desktop

  • Use the AMSTLOUT command to export your STL file.

  • The following command line options affect the quality of the STL and should be adjusted to produce an acceptable file.

  • Angular Tolerance – This command limits the angle between the normals of adjacent triangles. 

  • The default setting is 15 degrees. Reducing the angle will increase the resolution of the STL file. 

  • Aspect Ratio – This setting controls the Height/Width ratio of the facets. A setting of 1 would mean the height of a facet is no greater than its width. The default setting is 0, ignored. 

  • Surface Tolerance – This setting controls the greatest distance between the edge of a facet and the actual geometry. A setting of 0.0000 causes this option to be ignored. 

  • Vertex Spacing – This option controls the length of the edge of a facet. The default setting is 0.0000, ignored. 


  • File >Save a Copy

  • Set type to STL 

  • Set chord height to 0. The field will be replaced by minimum acceptable value. 

  • Set Angle Control to 1 

  • Choose File Name 

  • OK 


  • File >Save As

  • Select File Type >STL 

  • Enter a name for the STL file. 

  • Save 

  • Select Binary STL Files 


  • File >External >Save STL

  • Select Binary mode 

  • Select Part 

  • Enter 0.001mm for Max Deviation Distance 

  • Click OK 


  • File >Save As

  • Set Save As Type to STL 

  • Options 

  • Set Conversion Tolerance to 0.001in or 0.0254mm. 

  • Set Surface Plane Angle to 45.00 

  • Save 


  • File >Save As

  • Set Save As Type to STL 

  • Options >Output As=Binary, Unit = Inches 

  • Resolution > Custom, Deviation Tolerance = Minimum (Slide bar to right), Angle Tolerance = 5 degrees 

  • OK 

  • Save 


  • File >Save As

  • Set Save As Type to STL 

  • Save 


  • File >Export >Rapid Prototyping

  • Set Output type to Binary 

  • Set Triangle Tolerance to 0.0025 

  • Set Adjacency Tolerance to 0.12 

  • Set Auto Normal Gen to On 

  • Set Normal Display to Off 

  • Set Triangle Display to On 


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