Export to 3D file allows you to export all the models visible in the scene at once in a single file as a single object.


  • If you want to only export a selected model, use the dedicated function in File > Export Selected 3D Model, or Ctrl + Shift + E.
  • To export the drain holes as a separate 3D object is still available in File > Export Holes as a 3D file. 


  • If your model has a 3D hollowing applied to it it will be exported too.
  • If your model has drain holes you can activate (default) or deactivate the export using the check box in the 3D export palet.

Exporting the drain holes has some limitations:

The function of evacuation holes at 3D export allows removing polygons from the 3D model corresponding to the primitive dedicated to the function (Cylinder or cube), located on the model. 

This operation is done (currently) during the export phase of the 3D model in STL or OBJ format.

It is essential to make a difference between 3D export and the generation of the Slice file for the 3D printer: the benefit of exporting the 3D holes is if you want to use the model prepared in Lychee Slicer within another application. If you do not want to export your 3D model with the holes but only generate a slice file for your 3D printer, you do not need to use this function.

3D Drain Hole verification tool

Located in the Prepare > Hollow > Holes tool, the 3D Holes Conversion palette lets you find the holes that could be in error and wouldn’t be exported as a 3D model.

It’s composed of a detection feature, “Detect Holes in Error” and a real-time verification mode.

By pressing the Detect Holes in Error, Lychee Slicer will look at the validity of the hole in case you would export them as part of a 3D model export (STL/OBJ). If a hole is in error, it will be displayed in red color.

You can turn on the real-time verification mode that will check if a hole is valid while manipulating it. While this operation is fast, it can take more time to compute on a very dense 3D model and/or slow computer. If the real-time verification performance is not suitable for your scene, disable this mode and then use the Detect Holes in the Error function.

Each time you have a hole in error, please modify it, whatever its position, orientation or scale. We strongly encourage you to use the Advanced mode (Space bar) to edit your drain holes.

3D Drain Holes are not boolean operations

The function of converting 3D hollows to 3D topological holes on export is not a Boolean operation. It means this function is intended to make holes in the shell of the 3D model, after having created this 3D hollowing.

It is not intended to be used for cutting a model, such as taking a large cube of holes, to cut a model by removing one of the parts corresponding to the cube.

If you want to do advanced Boolean cutting operations, we invite you to use dedicated modeling software.

In the example above, the hole is used to cut a corner of the 3D model. You can do this operation using a drain hole during the slicing process, but you can't do it when exporting the 3D export model.

Drain holes validation for a 3D export

Our 3D drain holes are designed to be... drain holes! 

We have applied certain restrictions to make sure that the holes provide an optimum result and can also limit user errors. As mentioned before, they are not designed to perform Boolean operations, and as a result, the error handling is defined to meet the resin evacuation needs while also limiting the structural problems related to resin 3D printing. 

The different types of errors

In order for 3D recess holes to be valid, they must respect the following rules:

  • A hole can be exported only if the model has been hollowed. Inserting a hole in a model that doesn't have a thickness (and then with a hole that doesn't go through it) will result in an error.
  • A hole must intersect two surfaces and only two surfaces, one outside and one inside the 3D model. This requires that a hollowing out has been done previously, either in Lychee Slicer or in another application.
    • If a hole intersects a third surface, it will be ignored, and if the hole intersects more than one pair of consecutive surfaces, Lychee Slicer will generate only the first hole.
    • If a hole interests multiple wall thicknesses, only the one closest to the surface where the hole has been inserted will be generated

In this example, only the hole on the left will be created. On the right, the second wall will not have a drain hole.

  • A hole cannot partially intersect several surfaces on its side, otherwise, it will generate low-quality surfaces.

The hole is in error on the left because it partially intersects the adjacent surfaces. The hole diameter has been reduced on the right, removing all intersections with the side surfaces and making it valid for 3D export.

  • A hole may appear in error while it looks well inserted in the model. But a tiny part not respecting the rule can trigger the error system. If you look at the example below, a tiny part of the cylinder on the left is not outside the surface, making the hole cap intersect with the model and making the cylinder slightly longer will fix the problem.
  • Don't overlap holes to create complex drain holes shapes, like partially overlapping two holes to create an "8" shape.

To prevent this overlapping operation, overlapping holes will be resized, mainly reduced in diameter.

Exporting 3D Drain Holes

When exporting a 3D model in STL or OBJ file format from the Export section, 3D holes will be created. This operation is enabled by default but can be turned off in the Export > Export 3D palette.

A warning message will be displayed if a hole in error is detected, asking you to fix the holes before being exported. Then you will be moved to the Prepare section, and the application will display the holes in error.