How to edit and repair an STL file with 7 free STL editors: FreeCAD, SketchUp, Blender, Meshmixer, Meshlab, 3D Slash and SculptGL.
How do I edit STL files? That is something any 3D printer owner sooner or later wonders. After all: Ready-made STL files are fine. But what if an STL file you downloaded lacks some features, is damaged or you need only a part of it? That’s when you need an STL editor.
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Editing STL files can be done in two different types of modeling software:
On the one hand, there is CAD software (Computer Aided Design). It’s tailored for construction, provides exact measurements and solid modeling. These tools were not made for 3D printing in the first place. In CAD software, circles, for example, are “real” circles; in 3D printing – and in STL files for 3D printing – circles are represented as polygons. So CAD tools cannot show their full strength when editing STL files. Nevertheless, they can be used for working with STL files. Three of the four tools we present in this article are true CAD tools: FreeCAD, SketchUp, and Blender.
On the other hand, there are mesh editing tools such as MeshMixer and MeshLab. They are designed for modeling, animation, and objects represented by a 2D surface. That means: These objects have just a shell and no filling. This may cause paper-thin walls, which can’t be 3D printed, if the object is not solidified (which, however, can easily be done in tools such as Meshmixer). In fact, mesh editors are excellent tools when it comes to editing STL files.
FreeCAD is an open source and free to use CAD software. It offers many different tools for construction, like Drafts, Drawings, and Design features. You can download FreeCAD for free from the FreeCAD project website. Simply select the correct version for your OS and install.
A serious limitation: FreeCAD has some problems with intercepting structures and may mess up the mesh when it contains intercepting edges!
Of course, there are many more features and tools to use. If you want to learn more about FreeCAD, visit this tutorial!
FreeCAD features an extensive mesh repair tool:
To export your object as an STL file again, select the last feature in the model tree. Then click on File > Export and select Mesh formats.
When using FreeCAD as an STL editor, you really notice its purpose. It is a CAD program to create exact and models for mechanical use, not for modeling. This is great when you want to construct technical objects. Sculpting a model in FreeCAD is very difficult; as FreeCAD lacks a free move-around 3D view, sculpting is nearly impossible.
SketchUp – formerly Google SketchUp – is a full-blown 3D modeling software that is now owned by architectural company Trimble Buildings. SketchUp is available as a commercial version called SketchUp Pro and as the free SketchUp Make edition. By installing different plugins, you can adjust SketchUp up to your personal preference. You can download the free SketchUpMake edition from their official website.
To import STL files in SketchUp Make you need to install a plugin first (this plugin is already installed in the Pro edition).
When you have the plugin installed go to File > Import… and set the file type to STL files. Browse for the object you want to open and import it.
In order for your STL file to be 3D printable, you have to check it for manifold vertices and other hitches. SketchUp offers no STL repair out of the box. However, you can choose from a number of free and commercial plugins that will do the job nicely.
Another great plugin you should try is called Cleanup. It allows you to get rid of superfluous or hidden geometry.
To export your model go to File > Export and select the .stl file format.
SketchUp is easy to use, runs smoothly and has all the tools to create a 3D model. However, it is missing some key features of an STL editor for example for creating a solid object or for translating the triangle mesh of an STL file to squares which are easier to edit.
Blender is an another great free program to either create models for printing, games or video clips. It contains many useful tools for example various algorithms for smoothening or interpreting a surface. It is also very easy to import and prepare STL files for modeling. However it will take some time to getting used to Blender, and due to its huge amount of different tools and commands, it can be quite obscure. It also requires a powerful PC to display some models, especially if you subdivide the model into many smaller tiles.
Apart from STL import, Blender offers a native STL repair tool.
To export your object go to File > Export > Stl.
Blender is a great STL editor if you want to create high poly models. It offers many tools to sculpt and work out fine details in models. However, it takes a while to getting used to working with Blender and as already said: When having a high poly object, it will require a lot of computing power.
MeshMixer is a free mesh editing program which you can download from AutoDesk’s website. It is very easy to edit STL files and also has a built-in slicer tool. This means you can send the edited model directly to your 3D printer to print it. If you want to learn how to prepare, repair or check your object for 3D printing with MeshMixer, visit this tutorial.
You can access more models by switching from basic forms to for example arms or legs. Drag and drop the object you want to insert. Use the different colored arrows to move or rotate to model. Use the little square in the middle of the arrows to scale the model.
To export your object go to File > Export and select the.Stl file format.
MeshMixer is one of the best tools to edit your STL files. It takes all occurring problems like the paper-thin walls into account. Working with MeshMixer as an STL editor is easy and useful if you just want to resize your model or change something.
MeshLab is a free open source program that allows you to view or merge, transform or repair STL, PLY, STL, OFF, OBJ, 3DS and many other file types as well as point clouds. You can download MeshLab for free from the Sourceforge project website.
To open a supported mesh file go to File > Import Mesh and browse for your model.
MeshLab does not have the tools to create new vertices or objects. However, it is a great tool to combine two meshes of a 3D scan. You can also remove parts of the mesh and repair holes in the model.
How to merge two meshes:
How to delete a section of a model:
How to repair your object or search for holes:
To export the model go to File > Export Mesh.
Even if MeshLab does not offer the option to create new objects, it is a great STL editor to combine or repair a mesh. Using MeshLab is a great and easy way to combine the mesh of a 3D scan or just to create new models by merging them.
3D Slash is a free and easy to use 3D modeling software that lets you create models using a simple building-block concept similar to Minecraft. You can download 3D Slash for free or even access the free STL editor on your browser.
To open an STL file go to Start a new model and choose From a 3D file. You can browse for your file on the hard drive or drag and drop it into the browser.
The mesh has automatically been converted into a pixelated object that can be edited with 3D Slash.
You can add various primitives to the scene to get started with a new project.
3D Slash will be especially gratifying for hobbyists who occasionally want to create their 3D designs without having to master the mysterious lore of conventional 3D modeling software. If you are a beginner with aspirations of going pro one day, you will be better off with a traditional free STL editor like TinkerCAD.
SculptGL is a free 3D sculpting tool. Unlike its professional cousins, like ZBrush, SculptGL includes only the basic tools necessary and allows you to give you a sense of the sculpting workflow – all in the comfort of your web browser.
One serious flaw is that this program can occasionally produce non-manifold vertices.
Define the big features of your mesh (arms, heads, limbs) with a large tool. Move to smaller brushes for details.
When you realize that the STL file’s surface is degrading or you wish to add smaller details you should increase the resolution. There are two options:
SculptGL is a great way to get started in 3D sculpting. For anyone curious about 3D sculpting, this is the best free STL editor, to begin with. But once you try ZBrush or Mudbox, you realize what else is possible with this fascinating approach to STL editing.