A Complete Beginner’s Guide to 3D Printing

General tips for everyone and specific tips for Prusa I3 MK3S​ users to get started with 3D printing

Parmin Sedigh
Geek Culture
6 min readDec 31, 2021


Photo by Kadir Celep on Unsplash

Watching an entirely new object being created out of some plastic is extremely satisfying, and it’s something I’ve been fortunate enough to witness through the magic of 3D printing.

Ever since I found out that my local library has a 3D printer, a Prusa I3 MK3S​ to be exact, I’ve become somewhat obsessed with 3D printing. I’m by no means an expert but as a complete beginner who has had to figure out how to find good 3D models, slice them, and print them, I think it’s important that I share my experience. So let’s dive into all of these topics and learn how to 3D print.

Note that I will be discussing the Prusa I3 MK3S specifically as that is what I have used but the first few topics I’ll discuss (about dealing with 3D models) apply to any printer.

Step I: Finding a Model

Naturally, the first step is to find or create a model you’d like to print out. This could be anything from a figurine of your favourite character to something functional like a keychain or a prototype. The choice is yours.

Gif by author. A Prusa I3 MK3S at work.

I’ll walk you through my personal experience; I wanted to print out a model of the human brain, but I didn’t want to create my own model as I was sure that there must be some suitable model out there. The 3D community is very active and so after some searching, I found exactly what I was looking for.

So how did I find it? Through lots of searching on websites like…

  • Thingiverse: As far as I know, this is the most popular website for finding 3D models. It has lots of users, and even better, many of them comment after printing out the models, giving you clues as to what you should do. For example, I learned from a comment that I should make a certain part of the model slightly smaller so that it would fit well with the other parts. Plus, the search function of the website is quite strong with good filters and categories. Oh, and did I mention that all the models are free?
  • MyMiniFactory: This is a great place to look in case you don’t find what you’re looking for on Thingiverse. It has some very unique models but beware that some of them do cost money.
  • Pinshape: Similar to MyMiniFactory, there are some great free models as well as some that you need to pay for. On the plus side, if you decide to begin making models yourself, you can sell them on the platform.
  • YouMagine: Though I don’t find the search function of this platform very robust, it’s great if you don’t have a specific model in mind and simply want to find something to print. They have a way to look at their Popular and Trending designs as well as different collections such as “Quick Prints” to get you started.

What if you’d like to create your own model instead? That’s where I’d recommend finding a different resource as it isn’t my area of expertise. I have, however, heard that Tinkercad is a great platform for beginning your 3D model creation journey.

Step II: Preparing Your Model

When you’ve downloaded your model, chances are that it’s either a .stl or .obj file, both common file types for 3D models. But you can’t print this file type directly on the Prusa I3 MK3S and we need to go through a process called slicing.

Before we get there though, we first need to resize the model (if you’d like to). Going back to my example of the brain model, I wanted to make it slightly smaller. And I did that using a free program called Ultimaker Cura. You can download it here.

Here are step-by-step instructions of what you’ll do next…

Gif by author. A demonstration of how to resize and slice using Ultimaker Cura.
  1. Start by launching the app.
  2. Select your printer by clicking on the dropdown menu on the left. Then, click “Add printer.” If you’re using a Prusa I3 MK3S, click on “Add a non-networked printer” and then find your printer. This makes it so the correct printer bed size is displayed and that helps you set the right dimensions for your model.
  3. Drag your .stl or .obj file into the app and watch it appear.
  4. Click on the model to select it. Then, move it around if you wish to.
  5. To resize, click on the second option from the left-hand side menu. Make sure “Uniform Scaling” is on and then resize how ever you’d like.

Once you’re done with this, we can get to the slicing. All this is doing is changing the file type from a .stl or .obj to G-code which is the only file type the Prusa I3 MK3S​ can print from.

Before we slice it though, you should insert your SD card into your computer. Another limitation of the Prusa I3 MK3S​ is that it can only print from SD cards. We also need to ensure that the SD card is formatted in FAT32. If you’re a Windows user, you can find how to do that here and if you’re a Mac user, click here.

Once that’s done, we’ll return to Ultimaker Cura. See that blue “Slice” button in the bottom right corner? We’re going to click on that. If your SD card is inserted, you’ll see an option to directly save to the SD card. And voila, your file is ready to print.

Step III: Printing

With all of that preparation out of the way, it’s finally time to print!

Let’s begin by cleaning the printer bed. You can use isopropyl alcohol for this.

Now you can load the filament. I’m using PLA (a specific type of filament) so that’s what you’ll see me selecting. You’ll first place the spool of filament on the handle on top of the printer. You’ll then cut the end of the filament at a sharp 45-degree angle. After that, select “Load filament” from the printer screen and choose the filament type you’re using.

Once the extruder (the part of the printer that extrudes the filament) has reached the correct temperature, the screen will prompt you to insert the filament. No need to press the filament in too hard, just guide it until it’s being pulled in by the printer itself.

Video by author. A demonstration of how to load filament.

Next up, the printer will begin extruding the filament, hoping to clean out the previous colour that was in there. Just follow the instructions on the screen until you’re only seeing your new colour.

Once that’s all done, it’s time to insert your SD card! Once inserted, the contents of your SD card will be displayed on the printer screen. Use the knob to select the correct file. Then stand back and watch as your model is printed.

Once done, gently remove your model and unload the filament (unless you plan to use the same filament for another print within the same printing session.) Select “Unload filament” from the printer screen and then the filament type. When the printer is ready, you’ll be prompted to gently pull out the filament.

Video by author. A demonstration of how to unload filament.

That brings us to the end! In case you’re curious, here’s a final picture of my completed model of the brain. (The model is from Thingiverse as mentioned before and was created by Laweez.)

Image by author.

Now it’s your turn. Go out there and create some cool things using 3D printers.

Additional Resources

Here are a few other good resources to help you master the art of 3D printing.

Hey there. I’m Parmin, a 16 y/o student researcher studying stem cells 🧪Everyday, I aspire to learn something new! Make sure to follow me on Medium to hear about every new article I post, connect with me on LinkedIn, or contact me at parminsedigh@gmail.com. Also subscribe to my monthly newsletter to learn about everything I’m working on ✍️



Parmin Sedigh
Geek Culture

Science communicator trying to learn something new everyday | Published in Start It Up, Predict & The Writing Cooperative