Blender for 3D Printing: The 5-Minute Guide to STL Editing

Whenever my colleagues ask me to edit a 3D model in Blender, they’re always surprised when I give them the result just a few minutes later. They often tell me they want to learn to use it too, but it’s quite intimidating compared to tools such as PrusaSlicer. Luckily for them (and you!), we have just released a Prusa Academy course about Blender.

Blender is a free, open-source software primarily used for 3D modeling, rendering, and animation. But it can also do much more: 2D animation, VFX, video editing, physics simulations… With so many possibilities (and a correspondingly complex user interface), it can be very overwhelming for beginners. Which is a shame, because the 3D editing tools themselves are not that difficult to learn; they are just hidden behind several layers of unrelated features.

That’s why we created the Beginner’s Guide to Blender for 3D Printing: Edit and Remix STLs. The course is all about editing existing 3D models you find on Printables or other model-sharing sites. By limiting the scope, we can walk you through the essential tools without diving into the more complex world of building models from scratch, where most tutorials tend to start. Still, we cover various techniques, including direct mesh editing, sculpting, and modifiers.

This article is a sneak peek from the Blender course. It’s the first of many hands-on projects. You’ll see that you can start editing STL files in under five minutes. Honestly, downloading and installing Blender takes longer than that!

As a reminder, all Prusa Academy courses combine structured text, images, and short videos (usually just 5 to 20 seconds long, each showing a single step). You can easily skip what you already know and jump back to anything you want to review. It’s a great alternative to searching through long YouTube videos just to find that one bit of information you need. There are also quizzes along the way to test your knowledge, and upon completion, you get an official Prusa Academy certificate.

Just a quick note before we start: For better visibility, some of the videos only show the relevant section of Blender’s user interface. While the program might look slightly different on your computer, you should be able to follow the instructions without any problems.

Downloading and importing the model

For the purposes of this article, we skip over downloading and setting up Blender. If you don’t have Blender already, head over to the official site and download the version for your operating system (Windows, Mac, or Linux). The installation should be fairly straightforward. If you have any difficulties, please refer to the official Blender documentation.

As our example STL, we picked this vase from Printables. It has two main advantages: it’s a fairly modest design that lets you try out various editing styles, and it has a simple mesh (i.e., its geometric structure), which means it’s quick to edit even on a relatively slow computer (unlike extremely complex models, which can seriously slow your computer down).

Open its page to download the STL file.

Start a new Blender scene by opening Blender and selecting New File → General. If you already have Blender open, you can also use the top menu and go File → New → General.

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The default new scene in Blender has some basic objects (Cube, Camera, Light). These are used for 3D rendering. We don’t need those, so let’s get rid of them. The quickest way to remove everything in the scene is to have your cursor in the 3D viewport (the main area), press A to select all, and then press Delete.

Now, let’s import the vase file into Blender.

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The easiest option is to simply drag and drop the STL from your file explorer into the Blender window. A pop-up window appears with some options; just press Import STL to proceed. You can also use the top bar to navigate to File → Import → STL, then select the vase file from your computer.

Preparing for editing

When you import the vase, it might fill the whole screen and even extend off-screen. You can zoom out using the mouse wheel.

Alternatively, to quickly focus the view on the whole vase, select it with the left mouse button, then use View → Frame Selected in the top menu bar.

The default view mode in Blender is Object mode. This mode is similar to working in PrusaSlicer: you can only adjust the object’s size, rotation, and position. To modify the vase’s underlying shape, you need to enable Edit mode, which lets you change the relative position of individual edges and vertices that form the model.

In the top-left corner, select Edit mode from the dropdown menu. In the top-right corner, select Wireframe mode from the Viewport shading selector (the left button in a row of four circles).

The Wireframe mode lets you see through the model. This is helpful for evenly selecting all elements around the vase’s perimeter, including the base. To re-enable the default view, reselect Solid mode (the second button in the same menu).

Next, we need to align the view so we can see the vase perfectly straight on. We can use the navigation gizmo in the top-right corner. Press one of the circles at the ends to switch to these views: X or Y for front/side views; Z for top/down views. We primarily use the front view.

As a final preparatory step, we need to enable Proportional editing using the button with concentric circles at the top. This is important to create smooth shapes on the vase.

One last note before we change anything: If you make a mistake at any point, you can simply undo it with Ctrl + Z. This kind of editing is not an exact process, so it’s completely normal to just undo and redo everything a few times until it looks right.

So, let’s finally get editing! First, we will use the Scale tool to adjust the vase’s bottom part. We will use keyboard shortcuts, which are essential for most Blender workflows.

First, left-click and drag your mouse to draw a selection box over the lower section of the vase. You should see individual elements get highlighted. Then, press S to enable the scale tool, and move your mouse away from the model to increase the size of the selected part. Left-click is used to apply the transformation, but we don’t do it just yet. You can also cancel the tool at any time by pressing Esc.

Next, scroll the mouse wheel up and down to adjust the size of the proportional editing, as indicated by the grey circle. It can be counter-intuitive: scrolling down increases the size, and scrolling up decreases it. The larger the circle, the further the scale tool affects the rest of the vase. You need a relatively large size in order to achieve a smooth transition.

Finally, press Shift + Z to disable scaling along the Z axis (i.e., up and down). In other words, the segment gets wider, but its height doesn’t change. This significantly affects the shape of the vase, which you can again adjust by scrolling the mouse wheel. Finally, press the left mouse button or Enter to apply the modifications.

And with this, you have successfully edited a model! Before you export it, it’s a good idea to inspect it from all sides.

Switch back to Object mode to hide the wireframe. Then, press and hold the mouse wheel and move the mouse around to rotate the view around the vase. In this case, it should look symmetrical from all sides.

If it’s not symmetrical, you might have accidentally selected only the forward-facing parts of the vase, which is a common mistake. Undo (with Ctrl + Z), and make sure the wireframe mode is enabled before trying again.

Exporting and slicing

To export the edited model, use File → Export → STL.

In the pop-up menu, navigate to the destination folder, enter a name for the new STL file, and press Export STL at the bottom.

If we open PrusaSlicer and import the original and the edited vase side by side, we can see that the scale has been preserved. We can easily slice and print it!

Additional editing tools

The vase is a simple, versatile base that can be creatively customized in many ways. Let’s try some more variations. You can undo any existing edits with Ctrl + Z. Or simply remove the vase (with Delete) and import it again.

Apart from scaling, rotating is also a surprisingly simple and powerful tool for this model. You can enable it by pressing R.

In this example, we select the middle section of the vase and activate the Rotate tool with the R key. Then, we move the mouse to adjust the rotation angle and use the mouse wheel to change the size of the proportional editing. If the grey circle (i.e., the proportional editing size) does not touch the top and bottom of the vase, both will remain completely flat.

Of course, you can combine twisting with scaling as well. A larger base will make the vase more stable.

Another simple but effective method is to select thin stripes from the vase and rotate them with a smaller proportional editing size. If you repeat this several times with various rotation angles, it will “crumple” the vase.

As you can see, using these simple tools lets you create a completely new shape in just a minute. Try making your own variations!

Pro tip: after pressing S or R, you can use the X, Y, or Z key to scale or rotate along that axis only. This can be used to break the object’s symmetry.

Checking printability

There are virtually infinite shapes you can create this way. However, there are also many ways in which you can accidentally break the geometry. This typically means making the walls too thin or creating overhang angles that are impossible to print. Always check your edited STL file in the slicer before printing. This will help you prevent many errors.

For example, the first vase we made has very steep overhangs at the bottom (as indicated by the blue lines in the slicer). This can be solved simply by enabling supports.

On the other hand, this shape we created had walls so thin that PrusaSlicer even generated empty layers, which would obviously ruin the print. This issue must be solved by readjusting the vase in Blender.

Pro tip: Later in the Prusa Academy course, we introduce the Inflate Brush in the sculpting environment as an option for creating thicker walls.

Printed results

And here are two of my favorite remix designs, alongside the original simple vase. The decor is completed with these roses from Printables.

I didn’t actually really like how the original straight rose stem was poking out of the wavy vase, so I used the same method to add a twist to the stem. These custom-fit adjustments are the real beauty of STL editing in Blender!

Using the same general method, you can resize and reshape almost anything in Blender, so give it a try with your model of choice!

Of course, there’s more to it: for functional parts, you need to learn how to scale to precise dimensions. And for very detailed models, it might be better to use a modifier instead of direct editing. We cover these topics in detail in our Prusa Academy course. If you’re interested, check out the course and start your Blender journey today!

Happy learning!