What Program/Software Can Open STL Files for 3D Printing?

There are many programs and software you can use to open up STL files for 3D printing, but some are better than others. Some people wonder which files these are, so I decided to write this articles to help answer this question.

Keep on reading for more information about programs for STL files as well as more related information that you should find useful.

What File Type/Format is Needed for 3D Printing?

The G-Code file format is needed for 3D printing. In order to get this G-Code file, we need to get a STL (Stereolithography) file processed within a slicer software like Cura. STL files are the most popular file format you’ll hear with 3D printing and are needed to create the main G-Code file.

From a technical point of view, an STL file is an approximation of a 3D model using several size triangles to build the object up. This is known as tessellation and can be created by most CAD software out there.

Although STL files are the most popular, there are other files you can use in 3D printing depending on the machine and software you are using.

Keep in mind, these files are there to be converted to STL files, which can then be processed in your slicer to create the G-Code file which is needed for 3D printing.

Files that are supported in Cura (popular slicer) are:

  • ­3MF File (.3mf)
  • Stanford Triangle Format (.ply)
  • Wavefront OBJ File (.obj)
  • X3D file (.x3d)
  • JPG image (.jpg)
  • PNG Image (.png)

Yes, you can actually directly convert 2D images into Cura and process them into a 3D shape. All you have to do is drag the file into Cura and it will do it for you.

You can choose specific settings for .jpg files such as Height, Base, Width, Depth, and more.

What Programs Can Open STL Files for 3D Printing?

STL files can be opened by three categories of software; Computer-Aided Design (CAD) software, Slicer Software, and Mesh Editing software.

CAD Software

CAD (Computer Aided Design) is simply the use of computers to assist in the creation of designs. It existed before 3D printing, but has been used extensively to model some amazingly precise and highly detailed objects that a 3D printer can build up.

There is a range of CAD software that are made for beginners such as TinkerCAD, all the way up to professionals such as Blender. Beginners can still use Blender, but it has a pretty big learning curve compared to other CAD software.

If you wonder what programs create STL files, it would be some of the CAD programs listed below.


Tinkercad is an online free 3D modeling program. It is simple to use and is made up of primitive shapes (cube, cylinder, rectangles) that are combinable to form other shapes. It also has features that enable you to create other shapes.

Importation of files can either be 2D or 3D, and it supports three types of files: OBJ, SVJ, and STL.

The con is that it cannot function without internet, but this can also be a pro since you can access it without downloading some memory-heavy software.


FreeCAD is an open-source 3D parametric modeling application that is widely used for 3D printing. As you can tell by the name, it is a free software to use, and has a thriving community/forum that you can participate in.

You can create some real simple or complex designs using this application and easily import and export STL files with it.

Many people describe it as a great choice for beginners of 3D printing to start making their first models.


SketchUp is a good software that can get you ahead as a new CAD designer. It was formerly called Google SketchUp but has been acquired by another company.

Its key merit is the fact that it can open any STL file and it has the tools to edit them.

SketchUp has a wide range of applications from gaming to film and mechanical engineering, though for us 3D printer hobbyists, it’s great for creating our initial 3D model designs for 3D printing.


Blender is a very well-known CAD software in the 3D printing community which can open STL files. The range and ability that this software has is beyond your imaginations.

For 3D printing, once you learn this software, your capabilities can improve drastically but it has a steeper learning curve than most design software.

If you want to create or open STL files, Blender is a great choice as long as you take the time to learn it with a few tutorials.

They do constant updates to keep their workflow and features up-to-date and thriving with the latest advancements in the CAD field.

Mesh Editing Software

Mesh programs simplify 3D objects into vertices, edges, and faces unlike the solid models of 3D designs that look smooth. Mesh models are characterized by their weightlessness, colorlessness, and the use of polygonal shapes to represent 3D objects.

Mesh can be created in the following ways:

  1. Creating primitive shapes like cylinders, boxes, prisms, etc.
  2. Make a model from other objects by making use of ruled lines around the object to be modeled. This object can be two-dimensional or three-dimensional.
  3. Existing solid 3D objects can be converted into mesh objects
  4. Creation of custom meshes.

These methods afford you the chance to model your 3D designs with ease in any way you want it and achieve the desired details.

Below is the list of mesh editing software that I compiled.


MeshLab has an open-source system that enables you to edit 3D triangular meshes and do other cool kinds of stuff with your mesh.

Meshes that don’t look too clean or well-rendered can be healed, cleaned, and edited into something more detailed and befitting.

Despite its relative difficulty to operate, users of MeshLab commend the speed at which large files are opened on it.

Autodesk Meshmixer

Meshmixer is a good mesh tool for editing and mending STL files that are broken. It is relatively easier to use unlike MeshLab and it has a good interface that helps with easy manipulation of 3D objects.


This is a mesh editing software that works very well to fix STL files that could have errors or corruptions that you didn’t quite catch.

There is plenty that you can do with this software such as hollow and repair, merging meshes into one, choose a specific quality level, and many other specific repair tasks.

You can use it directly with Blender and SketchUp as well as within the Cura slicer.

Slicer Software

The Slicer software is what you’ll be using before every one of your 3D prints. They create the G-Code files that your 3D printer actually understands.

It provides information such as the exact location of every nozzle movement, printing temperature, bed temperature, how much filament to extrude, infill pattern and density of your model, and plenty more.

It sounds complex, but it is really easy to operate since it consists of boxes to type numbers in or dropdown menus to select options.

Here is the list of slicers that can open STL files;


Cura is the most popular slicing software out there, created by Ultimaker, a well-known brand in the 3D printing space.

It provides you with an application that you can place your STL files in and see the 3D model imported directly onto the build plate of your 3D printer.


PrusaSlicer is another well-known slicer software that has many features and uses that make it a great contender. One of the most noticeable differences is how it can process STL files for both FDM filament printing and SLA resin printing.

Most slicers stick to just one type of 3D printing processing, but not this one.


This software specializes in resin 3D printing and has gone through many updates that give it amazing functionality and ease of use for every person out there.

You can open up STL files and do plenty of functions with them. The user interface is really smooth and provides a great experience for resin 3D printer hobbyists.

Lychee Slicer

The Lychee Slicer is a personal favorite of mine because it goes above and beyond in the space of resin 3D printing processing.

There are some awesome features that you won’t find in other slicers such as their professional and modern design, multiple views for 3D prints, cloud space for your 3D prints, as well as comment functions for how each of your 3D prints went.

If you want to open up STL files for resin 3D printing, I’d recommend using this slicer for sure. You can use this for free, but they also have their Pro version which I’d highly recommend. It’s not very expensive either!

Can You 3D Print Directly From STL Files?

Unfortunately, you cannot 3D print directly from STL files. This is because the printer isn’t programmed to understand the language.

It understands G-Code language which is a series of commands that tell the printer what to do, where to move, what to heat up, how much material to extrude, and much more.

Printing 3D designs from STL files is done when the printer interprets the instructions codified in the g-code layer by layer. This means the object is not exactly printed in 3D, but by overlapping layers of extruded materials from the nozzle of the printer.

Where Can You Buy STL Files From Online?

STL files can be bought on several websites that sell 3D designs and other graphic content.

Here are the lists of websites that you can buy your STL files.


There are an abundance of high quality models that you can purchase on this platform. If you have been 3D printing for a while and are looking for a next-level experience for your 3D prints, I’d recommend trying it out.

You’d be best to 3D print models using a resin 3D printer so you can make the most of the high quality and precise details that designers put into their work.


MyMiniFactory is a very respected 3D printing website that has some ground-breaking models among its arsenal. I’ve browsed their models several times and they never fail to impress me.

The paid models that you can get from MyMiniFactory are serious premium in quality, most of which are at very reasonable prices. They are usually cheaper than models from CGTrader, and many models are up to their standards too.


SketchFab offers a pretty good user experience in its display of models. Do keep in mind that they are not all 3D printable because some models are not designed for it.

You’re able to filter out STL files which should be ready to process and 3D print.

There are millions of creators amongst this website that provide some amazing models. They even allow collaborations between designers, where you can see their  showcases of models.


If you’ve ever wanted a website that has over 2 million downloadable 3D designs, you’ll want to try out STLFinder. They have so many models from all over the internet, some being free, while some are paid.

Although you can definitely get some high quality free models, I’d highly recommend checking out some of the paid models to really impress you. These are the models which you can 3D print and realize the detail that 3D printing can produce.


This is a search engine where you can find plenty of free and paid models from plenty of 3D print model websites. It isn’t too hard to navigate around with the search function, and you can find some top-notch paid models with serious detail.


PinShape is described as an online 3D printing community that allows designers to share and sell their 3D printable designs, as well as have people download and print those very models.

Similar to the websites above, they also have many free 3D models as well as some excellent paid models.

How To Convert STL Files to G-Code

If you wondered “do 3D printers use G-Code?”, you should now know they do, but how do we convert STL files to G-Code?

Here are the steps you can take on converting your STL files to G Code:

  1. Import your STL file into the slicer
  2. Add your printer to the slicer
  3. Adjust the model in terms of placement on the build plate and rotation
  4. Adjust the print settings (layer height, speed, infill etc.)
  5. Click the slice button and voilà! The slicer should display a graphical representation of how the object will look when sliced, and other estimations like the time it will take to print the object.

The resulting G-Code is in form of texts and numbers that are readable for the printer and something that you can learn to understand.

You do need to have knowledge of what the commands mean, but you can find a good resource that explains each command.

This combination of codes simply commands the printing machine on where to move and how to move. You can check out this video to learn more about G-Code.

It is called G-Code because most of the codes start with the letter “G”, some start with the letter “M”, but are still regarded as G-Code.

What Files Can Cura Open & Read?

Many people wonder what types of files Cura can open and read, and whether Cura can read G-Code.

There are plenty of files that Cura can read which you can find below.


Cura can read several files which include G-Code. The list of files Cura can read is not limited to G-Code alone but its variants which include:

  • Compressed G-code file (.gz)
  • G file (.g)
  • G-code file (.gcode)
  • Ultimaker Format Package (.ufp)

Do not forget that the primary function of Cura is to read STL files and slice them into layers that are readable for your printer. This readable information is what is called ‘G-Code’.

3D Models

  • ­3MF File (.3mf)
  • AMF File (.amf)
  • COLLADA Digital Asset Exchange (.dae)
  • Compressed COLLADA Digital Asset Exchange (.zae)
  • Open Compressed Triangle Mesh (.ctm)
  • STL file (.stl)
  • Stanford Triangle Format (.ply)
  • Wavefront OBJ File (.obj)
  • X3D file (.x3d)
  • glTF Binary (.glb)
  • glTF Embedded JSON (.gltf)


  • BMP image (.bmp)
  • GIF image (.gif)
  • JPEG image (.jpeg)
  • JPG image (.jpg)
  • PNG Image (.png)

How Do I Open a G-Code File?

You can open a G-Code file directly in Cura or other slicer software programs. There is an online application like gCodeViewer which is G-Code analyzer. You can visualize the G-Code layer-by-layer and show key information like retractions, print moves, speeds, print time, amount of plastic used and so on.

Cura is said to be able to open G-Code files also, as well as compressed G-Code files, and you can Preview the movement and look of the file.

Importing G-Code into Cura is easy to do. You just have to find the G-Code file and drag/import it into Cura to open the file up.

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