Bambu Lab filed a patent in November 2025 that bears a striking resemblance to the basic concept behind Bondtech’s INDX. The corresponding patent application CN122560413A was only published in August 2026, just a few days ago, and is therefore currently causing quite a stir in r/BambuLab - although apparently very few people have actually looked at and read the patent.

At its core, it describes an automatic changing mechanism for interchangeable printheads. Just like INDX, the basic idea is to automatically use different printing tools during a print job while maintaining the filament path - and at first glance, the tool itself also looks similar: a “plate” with a hotend and a PTFE tube sticking out of the top - a “1:1 copy”, just like Creality already demonstrated with “KliTek”.

Although the two concepts look similar at first glance (if you only look at the tool itself), they differ technically in their actual implementation - particularly in terms of which part of the printing system is exchanged and how it is mechanically picked up and placed down.

So what is different?

The core of the invention is the mechanical coupling of positioning and unlocking:

• The printhead is moved to the pickup/parking position.
• Through a defined movement of the rack, the nozzles are lifted and hooked into the hotend from the front/bottom.
• The same movement releases the locking mechanism when the hotend is parked.

In other words, the rack moves – just as the rack already does with Vortek. This is interesting because the tool-changing process is therefore no longer largely controlled by the movement of the printhead itself, avoiding unnecessary travel distances (as with Vortek or INDX).

In addition, the swapping of nozzles within these hotend modules also appears to be possible - something that is not the case with Bondtech, for example (There is no reason why this could not work, but INDX nozzles officially cannot be replaced separately without replacing the holder as well - but i'm sure this will be added at a later stage).

For comparison, INDX is essentially covered by, or based on, this patent specification: US20240051229A1. This is exactly where the comparison with CN122560413A becomes quite clear if you look beyond the images. The approach used by INDX, as pursued by Bondtech, has a rigid rack where the hooking is performed by the movement of the printhead - just as with many other 3D printers and CNC machines before it.

What does this mean?

Like many large companies, Bambu Lab files patents constantly, some of which eventually become products and some of which do not.

You have to distinguish between "troll" patents and implementation-ready patents. With the former, an idea is patented with a sloppy drawing; with the latter, there is a very detailed functional description - and somewhere in between there are also “defensive patents”, which protect an idea that is not yet fully developed in order to potentially keep others out.

The aforementioned patent related to INDX probably falls somewhere between the "troll" and defensive-patent categories, as there is not much more than the basic idea contained in it. The current Bambu Lab patent, on the other hand, seems to lean more towards the defensive side: it is not yet fully developed, but several aspects are described and illustrated in considerable detail.

For reference implementations, for example, the patent filed in January 2025, CN122401876A, describes the H2D toolhead with remarkable precision, while CN224510427U, filed in June 2025, describes the H2C (both were only recently published in July 2026). This should ultimately put an end to the rumors that the H2C was a rushed response to Bondtech’s INDX announcement. The product was already fully developed at that point and there was a reference implementation for the patent office.

The same applies to many other Bambu Lab products - the respective products were often released roughly half a year after the patent was filed. However, many ideas described in patents never see the light of day or are eventually released in a different form, because while the basic principle remains the same, the mechanical implementation differs.

For this nozzle-changing patent to really make sense, one major component is still missing: a new AMS with separate filament paths. This is visualized in the patent drawings, but is not described in greater detail.

In any case, the lowering rack offers the possibility of moving the filament paths further down and potentially reducing the “PTFE tube Hydra” that we have seen with all other implementations so far.

It will certainly be interesting to see what the future brings.

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Note: This post is an English translation of the post previously published in r/3DDruck (German). The content and analysis are the same; this version is provided for the English-speaking community.

You can find the original post here: Bambu Lab patentiert INDX-Klon - oder doch nicht?

Bambu Lab hat im November 2025 ein Patent eingereicht, das auffällig stark an das Grundkonzept von Bondtechs INDX erinnert. Die entsprechende Patentanmeldung CN122560413A wurde aber erst im August 2026, also vor ein paar Tagen, veröffentlicht und geht daher gerade in r/BambuLab etwas rund - angschaut und gelesen haben diese aber scheinbar die wenigsten.

Im Mittelpunkt steht ein automatischer Wechselmechanismus für austauschbare Druckköpfe. Wie bei INDX geht es dabei grundsätzlich darum, unterschiedliche Druckwerkzeuge während eines Druckjobs automatisch einzusetzen und dabei den Filamentpfad beizubehalten - und auf den ersten Blick sieht dieses Tool auch ähnlich aus: eine "Platte" mit einem Hotend und einem PTFE-Schlauch oben raus - eine "1:1-Kopie" wie auch schon Creality mit "KliTek" gezeigt hat.

Obwohl beide Konzepte auf den ersten Blick ähnlich wirken (wenn man nur das Werkzeug selbst ansieht), unterscheiden sie sich technisch in der konkreten Umsetzung - insbesondere darin, welcher Teil des Drucksystems gewechselt wird und wie dieser mechanisch aufgenommen bzw. abgelegt wird.

Also was ist anders?

Der Kern der Erfindung ist die mechanische Kopplung von Positionierung und Entriegelung:

• Der Druckkopf wird zur Aufnahme-/Ablageposition gefahren.
• Durch eine definierte Bewegung des Halters werden die Düsen angehoben und von vorne/unten ins Hotend eingehängt
• Durch dieselbe Bewegung wird die Verriegelung gelöst, wenn das Hotend abgelegt wird.

Sprich das Rack bewegt sich - so wie sich das Rack auch bei Vortek schon bewegt. Das ist insofern interessant, weil damit wird der Wechselvorgang nicht mehr weitgehend über die Bewegung des Druckkopfs selbst gesteuert wird und unnötige Verfahrwege produziert (wie bei Vortek oder INDX).

Zudem scheint auch das tauschen von Düsen innerhalb dieser Hotend-Module vorgesehen zu sein - was bei Bontech z.B. nicht der Fall ist (es gibt zwar keinen Grund, warum das nicht gehen sollte, aber INDEX-Düsen lassen sich offziell nicht separat tauschen ohne den Halter mitzutauschen).

Zum Vergleich, INDX ist im wesentlichen durch diese Patentschrift abgedeckt bzw. basiert darauf: US20240051229A1 Genau hier wird der Vergleich mit CN122560413A recht deutlich, wenn man nicht nur auf die Bilder schaut. Der Ansatz von INDX, den Bontech verfolgt, hat ein starres Rack, bei dem das Einhängen durch die Bewegung des Druckkopfs erledigt wird - so wie bei vielen anderen 3D-Druckern und CNC Maschinen zuvor auch.

Was bedeutet das?

Bambu Lab reicht - wie viele große Unternehmen auch - ständig Patente ein aus denen etwas wird oder auch nicht.

Man muss hier zwischen "Troll"-Patenten und implementierungsreifen Patenten unterscheiden. Bei ersteren wird eine Idee mit einer schlampigen Zeichnung patentiert, bei letzteren geht es um eine sehr detallierte Funktionsbeschreibung - dazwischen gibt es noch "Absicherungspatente", die eine Idee die noch nicht fertig entwickelt ist absichert, um andere ggf. auszusperren.

Das oben genannte Patent zu INDX dürfte irgendwo zwischen die Kategorie "Troll"- und Absicherungspatent fallen, da ist nicht viel über die Idee hinaus enthalten - das aktuelle Bambu Lab Patent hier dürfte in die Richtung Absicherung gehen, noch nicht fertig aber einige Punkte sehr detailliert beschrieben und dargestellt.

Für Referenzimplementierungen z.B. beschreibt das im Jänner 2025 gemeldete Patent CN122401876A ziemlich exakt den Toolhead des H2D und CN224510427U aus dem Juni 2025 den H2C (beide kürzlich im Juli 2026 veröffentlicht) - was auch letztlich die Gerüchte, der H2C wäre eine Schnellschussaktion als Antwort auf Bondtechs INDX-Ankündigung gewesen, endgültig beenden dürfte. Das Produkt war zu diesem Zeitpunkt fertig entwickelt und es gab eine Referenzimplementierung für das Patentamt.

Das gilt auch für viele andere Bambu Lab Produkte - die jeweiligen Produkte wurden dann etwa jeweils ein rund ein halbes Jahr nach Patent Einreichtung veröffentlicht. Viele Ideen aus Patenten sehen aber nie das Tageslicht oder werden dann in einer anderen Form veröffentlicht, weil das Grundprinzip zwar gleich bleibt, aber die mechanische Implementierung abweicht. Damit dieses Patent zum Düsenwechsel Sinn ergibt, fehlt eine wesentliche Komponente: ein neues AMS mit getrennten Filamentpfaden. Das ist zwar in den Bildern des Patents visualisiert, aber nicht näher beschrieben.

Jedenfalls bietet sich durch durch das absenkbare Rack die Möglichkeit, die Filamentpfade weiter nach unten zu versetzen und ggf. diese "PTFE-Schlauch-Hydra", die wir bisher von alle anderen Implementierungen kennen, eindämmen.

Man darf jedenfalls gespannt sein, was die Zukunft bringt.

Zusammengesetzte Hauptwörter sind in der deutschen Sprache nicht gerade eine Raketenwissenschaft: einfach aneinanderhängen, bis ein unleserliches Monster entsteht - aber dieses Beispiel (tatsächlich aus der Raketenwissenschaft) ist ein besonders schönes: Ammoniumperchlorat-Verbundtreibstoff.

Hier werden zunächst zwei Bestandteile zu einem zusammengesetzten Hauptwort verbunden und anschließend durch einen Bindestrich mit einem weiteren Bestandteil zu einer noch größeren Zusammensetzung verknüpft.

I went shopping today at Globus (a german hypermarket chain) - because food prices in Austria are outrageous and it is way cheaper right across the border - but let's not get sidetracked here:

Came by the "Fruchtgummi" (fruit gum) aisle - and if you look closely: this is basically just Haribo - and yes, if you walk down the aisle, you might encounter some other brands like hitschies - but the dominant species is definitely haribo gummy bears (mostly the yellow packages) followed by every shades and colors by haribo in mostly the blue boxes.

It is quite the inventory they have here - enough to assemble a few printers :D

Just stumbled across this in the local news and immediately thought: That looks familiar... Then it hit me: when is Gyroid finally going to become the default infill in PrusaSlicer?

For context: the giant lattice in the photo looks like someone scaled up a gyroid infill to architectural dimensions, though it is actually an evaporative cooler and this pattern is not infill at all. The interesting part here isn't even the geometry, though - it's the material. Researchers at TU Graz are 3D-printing evaporative coolers from a clay mixture containing sawdust and fungal mycelium. During firing, the organic material burns away, leaving behind a highly porous ceramic that can absorb and distribute water very efficiently. Combined with the large gyroid-like surface, it creates an effective passive evaporative cooling system.

Original article (german) here: https://www.tugraz.at/news/artikel/kuehlende-keramikwand

Now the important question: will Prusa jump on the bandwagon and release Prusament Mycelium Clay? I mean, Prusament Terracotta Light is nice and all but it doesn't really look like terracotta - the hue is a bit too red. Can we get something that's properly matte and clay-like? I want to print my own tiny terracotta army.

Just spotted this on the local news. The structure in the cover photo looked ... suspiciously familiar. That giant lattice really resembles a massively oversized gyroid infill, so i looked closer:

It is a gyroid structure, but not actuall infill - and the gyroid itself is imho actually the least interesting part, though. Researchers at TU Graz have developed a 3D-printed ceramic evaporative cooler that uses additive manufacturing to maximize surface area for passive cooling.

What's really clever is the "filament" they used. The parts are printed from a clay mixture containing sawdust and fungal mycelium. During firing, the organic components burn away and leaving behind a highly interconnected network of pores. The resulting ceramic can absorb and distribute water throughout its structure extremely efficiently, providing a huge internal surface area for evaporation - and therefore cooling.

This is also a great example of where 3D printing actually enables something difficult or impractical with conventional manufacturing. The complex gyroid-like geometry maximizes the exposed surface while keeping material usage low (and admittedly, it looks pretty cool too).

In their initial experiments, the researchers measured a noticeable temperature drop in the immediate vicinity of the water soaked ceramic elements. The long-term goal is to explore whether these additively manufactured ceramic structures could become a low-energy supplement to conventional cooling systems in buildings or urban spaces.

Original article from TU Graz (German):
https://www.tugraz.at/news/artikel/kuehlende-keramikwand

Gerade das hier in den lokalen Nachrichten gesehen - das Muster am Titelbild kommt mir verdächtig vor - das sieht mir sehr verdächtig nach Gyroid-Infill aus - nur irgendwie zu groß.

Aber worum gehts: an der TU Graz wurde ein Würfel entwickelt, der durch Verdunstungskühlung ihre Umgebungstemperatur senken kann - aber mit maximierter Oberfläche. Gyroid-Infill ist da das am wenigsten interessante - der Herstellungsprozess und das entwickelte Material ("Filament") klingt sehr spannen..

Gedruckt werden die Bauteile aus einer Tonmischung in die man Sägespäne ein Pilzgeflecht (Myzel) gekippt hat. Der Ton wird gebrannt und während des Brennens verbrennen diese organischen Bestandteile und hinterlassen ein fein verzweigtes Netz. Dadurch entsteht ein besonders poröser Werkstoff, der Wasser gut aufnehmen und über seine gesamte Struktur verteilen kann. Die große innere Oberfläche fördert die Verdunstung und damit die Kühlwirkung.

Dank 3D-Druck kann hier eine Geometrie erreicht werden, die mit herkömmlichen Verfahren nur schwer oder unmöglich herzustellen wären - und es sieht natürlich extra fanchy aus. In ersten Versuchen wurde in der unmittelbaren Umgebung der wassergefüllten Bauteile eine deutliche Temperaturabsenkung gemessen. Langfristig wird untersucht, ob sich solche additiv gefertigten Keramikelemente als energiearme Ergänzung zu konventionellen Kühlsystemen in Gebäuden oder im öffentlichen Raum einsetzen lassen.

Originalartikel bei der TU-Graz:
https://www.tugraz.at/news/artikel/kuehlende-keramikwand

Für alle die, die nicht in den englischsprachigen Subs herumlurken oder den ganzen Tag auf der Printables-Startseite verbinden, wo dieses Projekt seit mehr als 9 Monaten angeklebt ist (der englischsprachige CORE One Mini Projektartikel ist einer von nur 3 Artikeln, die auf Printables bislang über 10.000 Views erreicht haben).

Nach unzähligen Stunden CAD-Arbeit, Prototyping, Firmware-Anpassungen und ausgiebigen Tests hat das Projekt seinen wichtigsten Meilenstein erreicht: Der CORE One Mini ist vollständig funktionsfähig.

• Hardware fertiggestellt
• Firmware angepasst
• Slicer-Integration abgeschlossen
• Erfolgreiche Langzeit- und Belastungstests

Was ursprünglich als Experiment begann, ist heute ein voll einsatzfähiger Miniatur-Ableger des Prusa CORE One geworden. Viele Verbesserungen entstanden dabei nicht nur am Zeichenbrett, sondern auch durch das wertvolle Feedback der Community - vielen Dank an alle, die mit Ideen, Kritik und Unterstützung zum Projekt beigetragen haben!

Vollständiger Artikel hier:
CORE One Mini – It's Alive! The Prototype is Complete (englisch)

Wie geht es weiter?

Alle aktuellen Dateien sowie die vollständige Projektdokumentation stehen jetzt zur Verfügung:
Prusa CORE One Mini (Community Edition) auf Printables

Das Projekt wird weiterhin gepflegt und verbessert, es gibt schon einige Punkte auf der Todo-Liste die das Nachbauen vereinfachen und günstiger machen (bzw. auch teilweise beim regulären CORE One Anwendung finden können) und ich freue mich darauf zu sehen, wie viele von euch ihren eigenen CORE One Mini bauen werden.

Wenn euch das Projekt gefällt und ihr ähnliche Community-Projekte in Zukunft sehen möchtet, zeigt eure Unterstützung durch Kommentare, Feedback oder indem ihr das Projekt mit anderen teilt. Je größer das Interesse, desto mehr Zeit kann in zukünftige Verbesserungen und neue Ideen investiert werden.

Ein besonderes Dankeschön geht außerdem an Prusa Research und u/Tommy_Prusa3D dafür, den CORE One als offene Plattform entwickelt zu haben - genau das macht Projekte wie dieses überhaupt erst möglich.

Nun ein kleiner Spoiler:

In der Prusa-Community ist derzeit der einer der größten Painpoints, dass man beim nachrüsten von INDX etwas Bauraumvolumen verliert - von den 220 mm auf der Y-Achse verliert man weitere 15 mm, was den effektiven Bauraum des CORE One mit INDX auf 248x205x270 mm reduziert.

Meine Nachfrage bei Prusa direkt (Achtung, das ist keine offizielle Info - alles Buschtrommel, unter der Hand) ist, dass es wohl in absehbarer Zeit keine Pläne für eine neue Iteration des CORE One gibt, der mehr Bauraum, eine größere Bauplatte oder ähnliches (wie z.B. die Rückgewinnung des verlorenen INDX-Platzes) haben wird.

Auf Basis der Erfahrung, die ich mit dem CORE One Mini und dessen deutlich platzsparender Konstruktion gesammelt habe, weiß ich jedoch, dass es auf jeden Fall (mit etwas Denkarbeit) möglich ist, zumindest diesen verlorenen Platz zurückzugewinnen bzw. sogar noch etwas oben drauf zu schlagen, wenn alles gut läuft. Und diese Denkarbeit hat bereits begonnen:

CORE One with a 256x256 mm Build Plate? Yes - It's actually fairly easy. Here's why. (englisch)

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Wenn ihr das Projekt oder ähnliche Projekte um den CORE One unterstützen möchtet:

Solltet ihr eine Prusa-Maschine kaufen, könnt ihr beim Checkout im Prusa-Onlineshop den Referral-Code „@suit“ verwenden. Dadurch bekommt ihr Prusameter - sowie je nach Druckermodell noch etwas gratis Filament dazu und ich auch (die ich wiederum gegen Filament eintauschen kann).

Alternativ könnt ihr auch einfach meine Modelle auf Printables herunterladen, liken oder drucken oder Mitglied in meinem Printables-Club werden.

Außerdem habe ich eine GoFundMe-Kampagne eingerichtet, um die Kosten des CORE One Mini Projekts abzufedern. Vielen Dank an alle, die etwas beigesteuert haben - das hat geholfen das Projekt zu finanzieren.

I totally understand, that some people want to just print - but i expected something different in the Prusa space :)

maybe i should just put GT1.5 belts on the CORE One Mini instead - a reduced belt pitch on a Printer with a reduced volume seems like a good idea.

Hello there,

this little stress test turned into another 11-hour print on the CORE One Mini. I mainly wanted a nice model to demonstrate just how much you can fit into the available build volume as a single piece item.

The Benchy shown here is printed at 380 % scale and it fits "comfortably" within the build volume. With some tweaking of the motion limits and by utilizing the printer's overtravel, it would be possible to scale it even a bit further - but 380 is a nice, round number.

For reference, a standard Benchy in its default orientation measures 60 × 31 × 48 mm, while the CORE One Mini has a build volume of 180 × 180 × 200 mm.

This means:

• Default orientation: up to 300% scale (180 × 93 × 144 mm)
• Rotated 45° diagonally: up to 354% scale (212.5 × 109.8 × 170 mm)
• Using the space diagonal: Only gains a tiny bit more, so it's generally not worth the effort.

However, by rotating the model to optimally fill the available bounding box, you can reach 380 % scale, resulting in a massive 228 × 117.8 × 182.4 mm Benchy.

So remember kids: you will need math after school in your daily life - at least if you want to do shenanigans like this :)

Crucial part here is, that you need to tweak and paint supports manually else they would generate outside the build volume.

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For comparison, on a regular CORE One, the maximum Benchy size is about 416.67% scale in the default orientation and roughly 490% scale when tilted at an optimal angle - for INDX it would be a bit less.

I've tried to upload a proper preview of the CORE One Mini CAD model, but Printables appearantly does not show this 70 MB monster of a STEP file in the 3D Model viewer, instead it just shows the second file (which is the way less nice looking base plate).

As a workaround, I've uploaded a .3mf that is interpreted perfectly fine for the preview - also other single body step files are shown perfectly fine in the selection for the preview.

Is this intentional or a bug or is something wrong with my STEP file, that Printables won't like?

Model in question:
https://www.printables.com/model/1734194-prusa-core-one-mini-community-edition-diy/files

Long story: short - It's alive! Everything is done, I'm done - I can finally rest :)

The hardware is finished, the firmware has been adapted, the slicer integration is complete, and after quite a few stress tests and longer prints, the CORE One Mini has officially reached its original goal: becoming a fully functional miniature CORE One.

The full project update can be found as usual on Printables:
CORE One Mini – It's Alive! The Prototype is Complete

TL;DR:

• Firmware
• Slicer config
• Test prints
• Future outlook

The model page with the updated files is waiting for you:
Prusa CORE One Mini (Community Edition)

What now? Now it's your turn!

If you'd like to see this or similar projects continue, now is the time to be vocal. Leave a comment, share your thoughts, ask questions, or let Prusa know that you'd love to see a more affordable way of sourcing the required parts.

The more interest this project gets, the easier it will be to justify spending even more time on future improvements. And even if you don't intend to build one yourself, you can still help a lot: download, like and collect the model on Printables to give it a boost in the algorithm.

And if you know a YouTuber, blogger or creator who might be interested in the project, tell them about the CORE One Mini. The more people who see it, the better the chances of turning this prototype into something even bigger or let the lessons that I've learned become used again in the next CORE One related project.

So what do you want to see me doing next?

And a little PSA: don't nag our faviourite community manager u/Tommy_Prusa3D too much - I assume he's currently at Open Sauce, don't let his inbox explode ... yet.

Thank you for this amazing journey :)

Before wrapping this update up, I'd simply like to say thank you.

This project would have been a very different experience without the incredible support from the community. Whether you've been following along from the very beginning, commented on Reddit, suggested improvements, tested ideas or simply left an encouraging message - every bit of feedback helped keep the project moving forward.

Special thanks also go to everyone who challenged my design decisions. Many of the improvements that made it into the final prototype originated from discussions with the community rather than from my own workbench.

Finally, thank you to Prusa Research for creating the CORE One as an open platform that inspired this project in the first place. I hope the CORE One Mini shows what is possible when a passionate community starts building on top of great engineering.

I can't wait to see if some of you decide to build your own CORE One Mini - and I'm looking forward to seeing where the project goes from here.

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If you want to learn more about the project, make sure to checkout the main post "CORE One Mini - The Rocky Road to a Prototype." for the complete background and FAQ.

If you intend to buy a Prusa machine, you can use the referral code "@suit" at checkout in the Prusa online shop. This will give you some Prusameter points and 1 kg of free filament and i'll get some points aswell (which I can use for some free filament). Or you can just download, like and make some of my models here on Printables and even consider to become a member in my Printables club.

I've also set up a GoFundMe campaign to tackle the expenses. Thanks to everybody who has donated to the project and helped to make it a success - that means a lot and helps me covering the financial side of such projects.

I might regret posting this - but I'm feeling I need to do this.

Some of you might know me as the guy who wouldn't stop talking about squeezing a CORE One down to a 180×180 build size. Unlike most keyboard warriors, I actually built it (and promise: the last remaing files and the firmware will be released in a few days).

But yesterday, u/japinthebox asked a question that caught my attention and i got a bit sidetracked.

Are there any plans/ways to get 256x256 on the Core One (non-L)?

It's a perfectly reasonable question. I've asked myself the exact same thing before: Why didn't Prusa just do the obvious thing? (not just the size but for many things). And don't forget: with the release of INDX, the already modest build area effectively became even smaller.

What surprised me even more than the question itself was the response. Instead of discussing the engineering or just answering the question, a some people immediately jumped to really not helpful and somewhat toxic responses: "Just scale your model down."

Seriously ... what the firetruck? If you're printing something like a Gridfinity box, you can't just scale it down. It's supposed to fit other Gridfinity parts. That's not how dimensional systems work. Yes, you can split models into multiple pieces. I've done it. It's a massive amount of work, testing and post-processing just to print something that would have fit on a slightly larger bed - a bedsize, that is basically an "industry standard" nowadays.

Then came my personal favorite: "Just buy a bigger printer."

Not everyone casually drops another €1,500 because Reddit told them to. For many people, spending over €1,000 on a CORE One was already a huge investment - and the Prusa-Promise is, to have a product with a long lifecycle and possible upgrade-paths. Suggesting they simply replace it isn't advice - it's dismissive. So please don't do that.

I mean - we used to build things. Now we defend products. What honestly disappoints me is how quickly technical discussions turn into brand loyalty contests.

Questioning a design decision shouldn't be treated as an attack on the company - Prusa came out of the RepRap-Movement - the whole idea behind this is creating and iterating.

And don't get me wrong here: Prusa makes fantastic printers, but they're not perfect. The CORE One has several design compromises compared to other machines on the market - many of which could be improved without reinventing the printer. That doesn't mean the engineers are incompetent - running a company and creating a product for volume production is different from creating a product that is build once.

In short: it means product development is messy. Once a machine enters production, changing sheet metal, supply chains, assembly procedures, documentation, support training, inventory and certification becomes incredibly expensive. And with most engineering resources currently focused on INDX, it's understandable why those changes haven't happened - and also, lets not forget: when the CORE One originally launched, it was already very late to the party.

So ... back to the topic: is 256x256 actually possible?

Since I had that question in the past and got no answers from Prusa, that question bothered me enough that I opened my old reverse-engineered CORE One CAD model from late 2025 - before the CORE One L was announced.

Back then I assumed the internal chassis would already have enough room for future expansion. I expected at least one of these: enough clearance for a 256x256 mm bed (which had already become the de facto standard after the Bambu X1 series) or ideally 270x270 mm to accommodate 9 XL heatbed tiles.

So I started measuring and after quite a bit of CAD work, I was quite baffled that the 270x270 mm was not going to happen.

There's simply not enough room without fundamentally changing parts of the machine and the XY motion system - but theoretically possible (don't quote me on that - i don't want to spend another 9 months building a highly custom machine).

But what about 256 x 256 mm?

Surprisingly ... yes. Fairly easy. With a moderate amount of mechanical changes, the printer can achieve roughly: 254 x 262 mm motion limits with relatively straightforward modifications (2 sheet metal components and a hand full of 3d printed parts).

With a bit heavier lifting (still only 2 sheet metal components) a motion limit of 258 x 270 mm is possible.

The biggest obstacle isn't the mechanics, it's finding a compatible 24 V PCB heatbed in the required size.

What would it cost?

If someone were to build a self-sourced upgrade kit today, I'd estimate: 200 – 250 Euros in parts (custom made) and potentially less if produced at scale. For a fully assembled new Printer, the cost would be virtually the same as for the current CORE One.

And to be clear: I'm not saying Prusa should have shipped the machine this way and I'm not saying it's an easy production change.

I'm simply saying the original question deserved a technical discussion instead of dismissive anwers.

Sometimes the answer isn't "buy another printer."

Sometimes the answer is simply: "Let's see if we can engineer a solution."

And - you can quote me on that: It is fairly easy to build a CORE One with a 256x256 mm build plate.

The question is - like last year, when I proposed the CORE One Mini: is it a Prusa product or is it a DIY job? An this time i think, an official Prusa product is much more likely.

This week was all about the final hardware tweaks and another round of motion system testing, to verify nothing gets caught where it should not.

I redesigned the UPG vent block that opens the upper vent and made a new right-side toolhead arm (that is also compatible with the CORE One+) to have a bit more clearance. With those changes and final parts, the mechanical side of the machine is finally complete!

On the software side, I'm now happy with the machine start G-code (including the prime line - I've did some testing there), the firmware is mostly finished and because details matter, I even made a custom textured build plate for PrusaSlicer.

I've also published Step 7: Bodywork & Electronics on the Printables model page of the CORE One Mini.

Next up is polishing the machine profiles for PrusaSlicer and OrcaSlicer, finishing the firmware, and then it's finally time to print.

So here's my question: What should I print?

Don't suggest the mandatory Benchy - I'll print a few of those, promised. But what else would you like to see in the 180×180×200 mm build volume? And no, I won't print a solid cuboid - I don't need an 8 kg hunk of plastic.

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For the main project page, full updates and FAQ head over to Printables and read CORE One Mini - The Rocky Road to a Prototype

If you want to help the project: If you intend to buy a Prusa machine, you can use the referral code "@suit" at checkout in the Prusa online shop. This will give you some Prusameter points + a free Spool of Filament and for me some Prusameter aswell (which I can use for some free filament). Or you can just download, like and make some of my models here on Printables or even consider to become a member in my Printables club.

I've also set up a GoFundMe campaign to tackle the costs. Thanks to everybody who has donated to the project already - that means a lot and helps me cover the expenses and adds possibilties for further improvements.

I've been compiling the BOM for the CORE One Mini, and as part of that process I've listed every component required to build the complete Nextruder assembly.

Buying every Nextruder spare part individually from the Prusa Store comes to around 340 Euro. That total excludes various screws and spacers, the print fan (which is also reused on the INDX toolhead), the PTFE tube, and the swing arm.

If you subtract the printed parts, the cost is still around 295 Euro.

These figures also don't account for the fact that some components are available as part of bundles, such as the CORE One Maintenance Kit or the MK4 Spare Parts Bundle, which can reduce the overall cost.

So, if you're planning to buy a used Nextruder to upgrade your MK3.5 to a 3.9, or you're building a CORE One Mini and looking for a Nextruder, keep these numbers in mind. Do the math before you buy - if someone trying to charge more, you may find that purchasing the parts yourself is cheaper than paying inflated second-hand prices.

For reference, the most expensive parts are:

Hotend Assembly (62,90 Euro)
https://www.prusa3d.com/en/product/nextruder-hotend-brass-high-flow-0-40-mm/

Main Cable (32,90 Euro)
https://www.prusa3d.com/product/main-cable-1300mm/

Stepper Motor (38,90 Euro)
https://www.prusa3d.com/product/stepper-motor-e-axis/

Planetary Gear Assembly + PG ring (39,90)
https://www.prusa3d.com/product/set-pg-assembly-pg-ring/

Heatsink Asembly (52,90 Euro):
https://www.prusa3d.com/product/hotend-heatsink-3/

Roughly 230 Euros in total.

Die beiden Schrauben, zum Justieren der Idler-Spannung sind beim CORE One gut zu erreichen - beim CORE One+ hat man allerdings einen Arm ergänzt der die Lüftung automatisch öffnet und schließt. Dieser Arm ist (aus mir unerfindlichen Gründen) so konstruiert, dass er die hintere Schraube verdeckt.

Wenn man also die Schraube drehen will, braucht man entweder einen Sechskantschlüssel mit Kugelkopf oder man kollidiert mit Schraubendreher mit dem Arm und muss ihn zur Seite biegen und schief ansetzen. Das ist jetzt nicht so schlimm, weil die Schrauben recht locker sitzen und man kaum Drehmoment braucht um sie zu drehen, aber trotzdem ist das halt eine ziemlich schlampige Konstruktion seitens Prusa.

Glücklicherweise hab' ich einen 3D-Drucker - also einfach selbst einen Ersatz konstruiert - wem es hier genauso geht wie mir: das File gibt es zum Download auf Printables:

https://www.printables.com/model/1777872-core-one-printhead-cover-right-lever-without-obstructions

While designing and finalizing the automatic vent for the CORE One Mini, I got a bit sidetracked and ended up fixing something that has annoyed me on the CORE One+ ever since I got it.

Whenever you want to adjust the Nextruder idler tension, the rear screw is partially obstructed by the bend/spring of the right vent lever. You can get to it with a ball-end hex key, but using the standard Torx screwdriver is awkward (yes, wrong tool - but I am lazy).

So I redesigned the lever to provide proper clearance around the idler screws. The rear screw is now easily accessible without the lever getting in the way.

As a bonus, the new lever is compatible with both the CORE One+ and the CORE One Mini, so there's only one part to maintain going forward. A small quality-of-life improvement, but one that's already made Nextruder "maintenance" a lot less annoying.

Download on Printables (drop-in replacement, no software changes needed)

And fear not - the side-tracking is over, I'm already back at the Mini and the Software/Firmware :)