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The 7 Best Free STL Editing Software for 2021

The 7 Best Free STL Editing Software for 2021

Every 3D printing enthusiast has to learn how to edit STL files eventually. Even though there are many premade STL files that get the job done, you at some point encounter files that lack certain features. This is where STL editing software comes in.

There are two types of editing software that we’re going to explore. First, we have CAD (computer-aided design) tools that are mainly developed to be used in construction. They’re not tailored for 3D printing, but they can still be used to edit STL files. Secondly, we have the mesh editing software. These tools are made for animating and modeling, and even though they work with 2D surfaces, they are perfectly suitable for editing STL files.

But STL files are challenging to edit and experiment with. So, let’s get a better understanding of what the STL format is and choose the best free STL editing software to get the job done.

What is STL

STL is short for stereolithography. It is the most basic 3D format and one of the most common ones. The main purpose of this format is to transfer information from a 3D CAD model to the printer. But what makes it different from other formats used in 3D printing?

The main features of the STL format are that it sees each 3D face of an object as a triangular mesh. This is the main reason why it’s a simple file format. Therefore, instead of having a perfectly smooth surface, the STL model is actually made out of a very large number of tiny triangles that don’t overlap. In other words, we’re looking at tessellation.

By understanding this concept, we can improve the resolution of the STL object by boosting the number of triangles while simultaneously reducing their size. Of course, this will result in a larger file. However, there’s one drawback that deserves mentioning due to the nature of tessellation. Surfaces aren’t as accurately represented by STL files as other formats, such as OBJ, that use smooth splines instead.

What’s the advantage?

As mentioned, STL is a small file format, making it easy to share with others. But what’s even more important is the compatibility. STL files are recognized by most 3D printers and slicers so when you share your model with someone, chances are he or she will have easy access to it. Other file formats may not be recognized by certain printers or software, so STL is the safest bet, especially if you’re just starting out. KISS (keep it simple, stupid) is a principle that applies to 3D printing as well.

Using STL Editors

If downloading finished models is no longer enough for you and you want to have the ability to change them however you want, then you need to start using STL editors.

The first type of editor you can choose is based on CAD, which is good for overall 3D modeling. CAD has been around for decades and it’s still used by professionals today because it enables us to be extremely accurate in modeling space. However, keep in mind that 3D printer resolutions are limited so CAD is a bit of an overkill. You won’t be using many features outside of editing the STL files. Nonetheless, we’re going to explore a couple of free CAD-based tools to give you an idea about what’s out there.

On the other hand, we have mesh editing software. This type of modeling tool doesn’t focus on accurate modeling because it reduces your models to empty shells. It might sound like a bad thing at first when compared to CAD software, but this aspect actually simplifies things. As a result, mesh editing tools are highly popular in 3D printing communities.

With that being said, let’s start exploring some of the most popular free STL editing software, including both mesh editing tools and CAD-based tools.

The 7 Best Free STL Editing Software for 2021


As the name suggests, this CAD-based tool is open source and free to be used by anyone. It is popular among beginners and professionals because it relies on parametric modeling and you can insert your own features and measurements.

Initially, FreeCAD started out as software for engineering design, which means that you can perform detailed edits on your STL files. However, this tool wasn’t intended for high-level sculpting and therefore it’s difficult to obtain a smooth surface.

With that in mind, you can get started immediately with FreeCAD even if you don’t have an STL file to work with. You can use it to create your model from scratch. In fact, that’s what you should do at first to get used to the software and its many features.

The 7 Best Free STL Editing Software for 2021


This tool is an online service tool that checks the STL file for any errors. It also provides you with a lot of control over the STL file, making it easy to change the quality level, adjust the mesh, and reduce or increase the number of polygons. It even has an option for merging meshes.

The 7 Best Free STL Editing Software for 2021

MakePrintable is a good choice for fixing a variety of model-related problems such as flipped faces and intersecting objects. You can repair the STL file automatically or make your own adjustments.

Take note that MakePrintable is available for free only for educational purposes or it can be accessed on a trial basis.

The 7 Best Free STL Editing Software for 2021


This advanced tool can automatically detect various problems and fix them. Additionally, it’s loaded with features and it’s completely free.

Meshmixer is 3D printing software capable of editing, checking, and fixing STL files. Its features include mesh mixing, sculpting, creating patterns, hollowing, stamping, surface smoothing, and a lot more. It’s one of the most complete STL editing tools out there and you can use it for more than just editing.

The 7 Best Free STL Editing Software for 2021


This tool isn’t exactly an STL editing tool, but it’s still worth mentioning because it’s a useful viewer. Something, all you want is a way to check whether your STL file is error-free and usable. This is where FreeViewer comes in.

FreeViewer enables us to inspect the interior of the model and see how thick the walls are. Its user-friendly interface quickly alerts us if there’s anything wrong with the model and gives us the green light to start printing.

So if you’re still an inexperienced 3D-printing enthusiast who doesn’t know much about editing meshes and working with CAD tools, FreeViewer is the best place to start. Perform a quick quality check on your STL file and then switch to the slicer to handle the rest.

The 7 Best Free STL Editing Software for 2021


MeshLab is a free open-source program that enables us to edit STL files. We can use it to check, repair, edit, convert, render, and merge meshes. Furthermore, we can fill in any holes that we might find in the 3D model.

MeshLab is incredibly feature-rich and as a result of that, it’s not the most user-friendly tool out there. It’s best used with raw information coming from CAD software and to prepare the model before printing it. Some of the most valuable features are model visualization, color mapping, model reconstruction, and texturing. However, to get started you will need an STL file because you can’t create your model from scratch using MeshLab.

The 7 Best Free STL Editing Software for 2021

MeshLab is a popular tool for fixing and simplifying 3D models, so you won’t have issues finding thriving communities to learn from. There plenty of tutorials out there, including on MeshLab’s website and the developers even offer direct support. All in all, there’s not much more you can expect from free software.

The 7 Best Free STL Editing Software for 2021


This is another 3D printing tool that’s free with some fine print attached, but it’s worth adding to the list. Netfabb is available for education and therefore students can get their hands on this software for free for up to 3 years. This is one of the most powerful STL analysis and repair programs out there, so it’s worth giving it a shot, especially if you’re a student.

Netfabb can be used to optimize the 3D print production process as it also contains a number of design tools. You can use it to prepare your models quickly and generate supports without a hassle. Furthermore, build failures can also be prevented to a great degree thanks to Netfabb’s simulation capabilities.

The 7 Best Free STL Editing Software for 2021


Blender is a free 3D modeling tool that’s used in a variety of sectors. It’s used by engineers, architects, game developers, animators, and 3D printing as well. It’s one of the best options for an individual or a small company because it has a lot to offer when it comes to 3D design and modeling.

Another important point is that Blender isn’t just some limited freeware. It’s entirely community-driven and under constant development. Bugs are being routinely fixed, updates are regular, features are being expanded with every major patch, and it continues to evolve with the industry. Besides, it’s not just free for students or for private use. It’s free for commercial reasons as well, and that makes a huge difference for someone looking to start a small 3D printing business.

However, Blender isn’t just modeling software. You can edit existing STL files, repair them, add or remove various objects, mask your models, and much more. There are many tools you can use. In fact, there are so many tools for editing and sculpting that you can create any kind of surface you want. You can pretend your model is made out of clay and sculpt it, you can flatten any sections you want, inflate the model, and so on. Blender isn’t just a program, it’s a toolbox.

With that in mind, Blender is also user-friendly, but it takes time to learn every feature it comes with. The learning curve is only challenging because you have to memorize so many tools and what they’re used for. Fortunately, Blender has an enormous community of users and you will easily find online video tutorials and even classes that teach you everything you need to know. Simply put, Blender is the best all-around tool there is, and it’s free! That’s not something you can easily beat.

The 7 Best Free STL Editing Software for 2021

Final Thoughts

If you’ve been 3D printing for a while now, you must have quite a few STL files waiting to be used. Printing those original models might not be the most ideal choice anymore, so the next step in your learning process involves editing those files. To do that, you’re going to need to get your hands on an STL editor and practice using it.

If you’re a beginner at 3D printing, or if you never tried to edit STL files before, you should first try one of the many free STL editors. On this list, you’ll find some of the most popular ones that give you all the tools you need and much more. So try them out and take your 3D models to the next level!

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