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  1. This manual is for the Original Prusa i3 MK3 only! In case you have a new model MK3S, please proceed according to Original Prusa i3 MK3S kit assembly v3.12
    • This manual is for the Original Prusa i3 MK3 only! In case you have a new model MK3S, please proceed according to Original Prusa i3 MK3S kit assembly v3.12

    • The kit includes:

    • Needle-nose pliers (1x)

    • Philips screwdriver (1x)

    • Allen key (6x)

    • No soldering is required.

    • No wire crimping is required.

    Silly me - I went to get my tools before I opened the box. Thanks for including tools, and all the Allen keys. I was worried I might not have my own of the right size. Awesome kit.

    Mark Deley - Reply

    Hi Mark,

    all the tools for the assembly are always included. However, you can use your own, in case you find yours better.

    Jakub Dolezal -

    I appear to be missing the “Slotted screwdriver”, though this isn’t a big deal I do have my own. The Tool bag also does not mention it should be in there. So is it in another bag or box? I checked everything and cannot find it.

    Daniel Paschall - Reply

    Hi Daniel, all tools should be together in one bag. The size is 3mm, in case you are unable to get it in the nearest HW shop, please contact our support. Contact info is here: 1. Introduction

    Jakub Dolezal -

    I am also missing the slotted screwdriver. Perhaps the kit was modified to use only Phillips head screws. In any case, I have slotted screwdrivers, just in case. - Reply

    Hi, I'm sorry the slotted screwdriver is no longer part of the kit. However, this tool was not needed and was sent as an extra.

    Jakub Dolezal -

    I am also missing the slotted screwdriver

    Ettienne - Reply

    Hi, I'm sorry the slotted screwdriver is no longer part of the kit. However, you don't need it for the assembly.

    Jakub Dolezal -

    Mine does not have the slotted screw driver either

    Serhat Dinçer - Reply

    Hi, I'm sorry the slotted screwdriver is no longer part of the kit. However, it is not needed for the assembly.

    Jakub Dolezal -

    I received two manuals only problem one was in english the other was in some other language.

    The “Assembly Instructions” was in English.

    The other had this on the cover “Prirucka 3D TIskare”

    Can I get a replacement in English?

    Goddur - Reply

    Hi Goddur,

    sorry the second one is in Czech language, are you ok with the PDF version? Download it here:

    Jakub Dolezal -

    It would be nice to have an english hand book thereby allowing me to read it during my commute.

    Goddur - Reply

    Hi Goddur,

    then please contact our support at, we will send you the correct language version.

    Jakub Dolezal -

    Would someone mind sharing the sizes of the Allen keys? I prefer to use bits, and I’d like to make sure I have the ones I’ll need. Thanks!

    Brian Dobson-Lewis - Reply

    I too would have found useful to have a list of the allen wrench sizes…

    Bernard Higonnet -

    Especially as the two smallest ones appear to be the same size!??

    Bernard Higonnet -

    Please list “Optional Tools” in this section, based on people’s comments in the various sections on what tools they needed to make their particular kits fit together. I’m finding in my kit the press-fit joints require hand-drilling out the hole to make it possible to press the parts together. In particular, if I don’t use a drill, I can’t insert the Nylon filament (step 5.35) because my kit’s filament is 3.44 mm in diameter and the hole is smaller than 3 mm. I understand that an experienced printer assembler knows that press-fit printed joints usually require drilling, but I’m not an experienced printer assembler… yet :-)

    Brad Needham - Reply

    Now that I’ve completed the assembly process (24 hours of work for me; probably 8-12 for others), I can now say that your parts bagging and online manual are fantastic! The “Prepare the parts” picture before each step helped me keep things in the right bags until I needed them, and helped me see whether I had parts left over at the end of the step. It was also valuable to see other customers’ comments about what they had particular difficulty with and how they worked around it - I probably could not have successfully assembled my kit without their experience, and the helpful replies from Prusa folks.

    My advice to other kit assemblers: be patient and take plenty of time., especially in assembling the Extruder.

    My printer has now successfully turned on, self-tested, calibrated, done First Layer calibration, and printed a 20 mm calibration cube that is perfect! I’ll probably fiddle with the First Layer calibration a little more, but as-is my prints are coming out perfectly! Congratulations, Prusa team!

    Brad Needham - Reply

    Just unboxed and started assembly when I couldn’t find the slotted screwdriver. Even though I can easily grab a slotted screwdriver from my workbench, my confidence level in having all the actual printer parts plummeted. I then read the note in the manual about “We strongly suggest using the actual online version of manual…” and I see here that there is no slotted screw driver. Confidence is back soaring high. However, I couldn’t help think that if you can print an update to chapter 5 on a piece of paper and put it in the manual, perhaps you could have added a note about the slotted screwdriver no longer being needed. It sure would have saved some time and that sort of bad feeling that things aren’t starting off well. From these posts I see I’m not the only one who spent time trying to find a non-existent tool in the box. No worries, back on track…

    Rick - Reply

    If you are unfortunate enough to have received the wrong PINDA probe for the MK3, but fortunate enough to read this: Check the PINDA probe for Chapter 5 - step 28 now. If it has 3 wires as opposed to 4, and you are assembling a MK3, you’ll need to contact Prusa for a replacement. If you don’t check this, you won’t discover it until you’re 3 connections away from being done and will have to do extra work and wait to replace it. DO IT NOW.

    Troels Larsen - Reply

    Many comments are about “what torque to use” or “I broke this bit”. And video comments suggest that many people don’t know that their electric screwdriver has a torque dial ring. Don’t use power tools.

    The Allen keys are bent at a right angle with a long and a small part.

    My dad told me that the size of the key and the length of the parts are meant to tell you what kind of force to use. One of the very few advice he has given, that I still adhere to.

    I use the long part into the screw, in other words turning the screw by holding the short part of the Allen key. This allows for a certain amount of force. The “pain” in your fingers will tell you if you are using too much force. Sometimes the screw is a bit stuck, and you hold the Allen key on the long part, but you still have to think about the fact that you are screwing into a plastic thingy.

    Since we are dealing with plastic bits, I use the short part as a handle. Only the frame - purely metal parts - requires the long part as a handle.

    Jørgen Holst-Rasmussen - Reply

    My dad never told me that (he told me a lot of other things…) but I followed the same technique and it works well for this kit. I generally turned the short end of the Allen wrench, and when it stopped (or the pain became too great) I would sometimes reverse it and turn the long end but not more than 90 degrees. In general this seems to be a good torque for the plastic parts.

    Ybl84f1 -

    The question of:

    Would someone mind sharing the SIZES OF THE ALLEN KEYS???

    WAS NEVER ANSWERED, and would be of huge benefit to know, and IMMENSELY APPRECIATED, as my Kit lands tomorrow.

    Also, if one has a Precision Screw Driver with Adjustable Torque, what settings are appropriate for Metal to Metal and Metal to Plastic?!?

    Thank you in advance to whomever is able to provide definitive answers!!!

    David Shorin - Reply

    Hi David,

    for this assembly you will need following Allen keys (all are included):

    1.5 mm - pulleys

    2.5 mm - M3 screws

    3.0 mm - M5 screws (aluminium parts)

    Regarding the recommended torques, there aren't any specific values. My recommendation is to make the final tightening using your hand and keep in mind, it is a plastic part you are tightening, not a steel.

    Jakub Dolezal -

  2. All the boxes and bags including parts for the build are labelled.
    • All the boxes and bags including parts for the build are labelled.

    • Number (or numbers) in the header tells you for which chapter you'll need that bag (or box).

    would be cool to have printable pdf of this

    PaulHarris - Reply

    Hi Paul, already working on something ;)

    Jakub Dolezal -

    Rebuilding Extruder, Where can I get a pdf of E-Axis screws?

    John Tucker - Reply

    Hi John, there is no PDF available. Did you need a list of used screws and nuts?

    Jakub Dolezal -

  3. Most of the labels are scaled 1:1 and can be used to identify the part :-)
    • Most of the labels are scaled 1:1 and can be used to identify the part :-)

    During the yesterdays built I had several time the situation, that a screw or nut was missing.

    As there is the amount of parts on the bag this brings ne to the idea, that one bag with small bags for each kind of screw, nut, etc. would be easier to handle.

    You will have one bag with the plastic parts for each step with the description of the needed additional parts from the “nuts and bolts“ bag. No spare parts bag anymore, as you should deliver the needed quantity plus, let's say, 10%. No search for the little nuts, just one grip to the right bag.

    What do you think?

    Wolfgang Peters - Reply

    Hi Wolfgang, interesting idea. I will discuss this with my colleagues. Thanks.

    Jakub Dolezal -

    A printable reference sheet would be really helpful, especially when upgrading as we’ve usually gotten rid of the original bags by then.

    Gerry Campbell - Reply

    If you are doing official upgrades, then you receive the bags with reference labels again :) If you are doing community or self made upgrades, well then it is up to you which screws you want to use.

    Although, we will share PDF with all of the screws for each printer in the future (currently we are quite busy updating our MMU2 assembly manuals :/ )


    Tomáš -

  4. Every type of fastener is included in a separate special bag.
    • Every type of fastener is included in a separate special bag.

    • If you lose a screw when building, use one from this bag.

    Maybe it would be a bit clearer if the text says “spares” instead of “fastener”? It already says so on the bag and it makes more sense :)

    Paulo "JCranky" Siqueira - Reply

    This bag is used for spares :) that is true. We just mentioned that all of the fasteners have separate bags and spare bag should be used only if you loose one :)

    Tomáš -

    Agree with Paulo, the English phrasing on that is a bit awkward, maybe “Spare fasteners of every type…”

    Kadah -

  5. When you browse the guide on, you can view the original  images in high resolution for clarity.
    • When you browse the guide on, you can view the original images in high resolution for clarity.

    • Just hover your cursor over the image and click the Magnifier button ("View original") in the top left corner.

    Note on some of the steps where you have multiple pictures the Zoom feature doesn’t always work correctly, this tripped me up a couple of times. After selecting the picture via the thumbnail you need to click on the large picture to zoom, as opposed to the magnifying glass on the large picture. Many times there is no difference but for whatever reason on some pictures it matters.

    For instance in Chapter 8 (Electronics Assembly) Step 5 (Preparing the lower hinge) there are 3 pics. If you hover or select the 3rd thumbnail and click the magnifying glass it zooms correctly. If you select the second thumbnail and click THE MAGNIFYING GLASS it incorrectly zooms the 3rd picture. However if you select the second thumbnail and click on the picture (NOT the magnifying glass) it zooms the second picture correctly. This is true in both Chrome/Windows and on my iPad.

    I missed out on a few zooms because I click on the thumbnail and immediately on the magnifying glass!

    Ybl84f1 - Reply

  6. Starting with Original Prusa i3 MK3 most of the printed parts are marked with their version.
    • Starting with Original Prusa i3 MK3 most of the printed parts are marked with their version.

    • In case you have issues while assembling the printer with the certain printed part, please try to find this label and tell it to our support team.

    Nice idea to build the revision into the printed part.

    Mark Deley - Reply

    Is there an easy way to know which versions of which parts are the “latest”?

    Bret Toll - Reply

    Hi Bret, latest design is always uploaded to our GitHub and publicly available, BUT we are using different labels for parts printed in our factory and for the GitHub ( So you can easily compare the shape, but not the labels.

    Jakub Dolezal -

  7. Lost in the instructions, missing screw or cracked printed part? Let us know! You can contact us using following channels:
    • Lost in the instructions, missing screw or cracked printed part? Let us know!

    • You can contact us using following channels:

    • Using comments under each step.

    • Using our 24/7 live chat at

    • Writing an email to

    • You can start by assembling Y-axis in the next chapter - 2. Y-axis assembly

    Not sure where to put this comment as it regards the printed manual only.

    It would be very helpful if the printed manual had a series of black rectangles printed on the right edge of the page that moved down the page section by section with the step number printer in white in the .

    This would allow fast identification of the step (rather than in the top left seam of the page as it is currently) and also give visual indication from the edge of the book of the sectioning within the book. It would also make flipping through the book to find a section far easier.

    Kris Boyle - Reply

    Hi Kris, interesting idea! I will see what we can do regarding the printed version, as we generate brand new each time I update some steps.

    Jakub Dolezal -

    It was just a thought as I was doing the first step. I have now switched to using the online manual as I find the contents by everyone extremely helpful. Thanks everyone!

    Kris Boyle - Reply

Finish Line

1059 other people completed this guide.

Jakub Dolezal

Member since: 02/20/2017

222 Guides authored


Prusa Research Member of Prusa Research


3 Members

364 Guides authored


Thank you :)

Jakub Dolezal -

Nice touch on the version numbers! :D

Alex Tutusaus - Reply

Please add a link at the end to the next section of the manual.

Murray Foster - Reply

Hi Murray, link added. Thanks

Jakub Dolezal -

Good Start !!

Robert McClure - Reply

This is well done by someone that really cares about us the users … Makers.

I have never seen a procedure this well done.

Thank You for caring!

Rich Johnson - Reply

Merci, bon début!

Yves Sauget - Reply

Doc page is nicely done! Thumbs up for:

* 1-1 scaling size for parts in docs. Makes part IDs very easy.

* Part ID on each part

* Bag labeling that match doc chapter.

I’m still awaiting my MK3, but after reading this first chapter, my build-anxiety is already being eased!


Gene Dahilig - Reply

Great! Good job

Sirius - Reply

Might I suggest we be honest with ourselves, the first step is open the bag of included candy? Great Manual so far!

Luke Davis - Reply

No no no :) The candy comes only after some work is done ;)

Jakub Dolezal -

Very user friendly.


Anders Roer Jensen - Reply

Hi Anders, thanks for the feedback. Enjoy the build!

Jakub Dolezal -

Did you stop shipping the slotted screwdriver? It was missing from my kit.

Markus Carlbark - Reply

No slotted screwdriver in my kit either.

Matt Cantrell -

The manual is awesome. One suggestion would be to make a more prominent and clear button for progressing to the next chapter. The current link is too small and subtle, and I find myself drawn to the “Finish Line!” button as a false positive for moving on to the next section.

I’m being knit-picky, but I think it would help usability. Thanks!

Connor H - Reply

Hi Connor, I will try adjusting the text for better visibility. Thanks for the feedback ;)

Jakub Dolezal -

I was wondering why I don’t have the second screw driver in the package, and I see that you simply updated the product and didn’t manage to put the new printed version in the package. Great that new instructions are online. Thanks!

Artem - Reply


Give yourself a Gummy!

michael_farady - Reply

I already had enough of them :D

Jakub Dolezal -

I am glad that I looked here. The book in the kit was v3.04 so this is more up to date.

Joshua Reed - Reply

Hi there Joshua, online manuals are usually the most recent ones, we try to update the printed ones as soon as possible, yet sometimes there might be a slight delay.

Thank you for understanding.


Tomáš -

Just completed assembly of my MK3 yesterday. With patience spread out over several days and the help of this manual I successfully got it up and running after the first self test. This manual is easy to follow and if you take the time to read each section along with comments from others I see no reason for failure. This is my second printer, the first being a Creality CR10 which I’ve had great success with. I consider my purchase of the MK3 a giant leap forward in the speed and quality of my future prints! It was truly a great learning experience putting it together. I will be highly recommending Prusa printers to those who might be in the market for a outstanding printer. Thank you Prusa for being customer conscience.

Mike Kuechler - Reply

Hi Mike, thank you for the kind words. We are doing our best to make our printers stand out. I'm glad you've enjoyed the assembly ;)

Jakub Dolezal -

I began my build on Thursday 10/25/2018 of the i3 MK3 kit. Was unable to edit my profile until now (to stop it from posting my email address!), so these comments are after the fact. Very well documented process, hats off @jakoob for an excellent manual and support

Matt Laudato - Reply

Jakub is busy now, but he is happy that you like his manual. Thank you and happy printing!

Martin L. - Official Prusa CS -

First off, thanks for the gummy bears! Great touch! It would be nice to have a link to the next step at the bottom of the screen.

Christopher Rouxel - Reply

This has to be the most thorough, professional looking assembly manual that I have ever had the pleasure of using.

Robert Loper - Reply

Don’t want to sound ignorant, but is there a hardware list?

Bayden Wintet - Reply

Hello Bayden, There is a list of all packages in the kit, and then on every package there is a label with 1:1 picture and description of its contents.

Martin L. - Official Prusa CS -

I love the way you guys package everything and your instructions are awesome!

Chris Willoughby - Reply

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