We’re now launching the orders for the MMU3 compatible with the Prusa CORE One. We have two official “flavors” and one special community version. And conversion kits, too! There’s definitely a lot of ground to cover – as always. 🙂

However, before we get to that, I’d like to give you an explanation of why this news came a bit later than originally planned. Our initial goal was to have the MMU3 ready by the end of April, but we needed a couple of additional weeks. During development and testing, we looked at more solutions (not just a 1:1 conversion of the MMU3 from the MK4S), and as a result, we can now bring you several different packages, and we also made important steps towards a next-gen multi-spool system.

Printing with colors on the CORE One

Just in case the CORE One is your first Prusa 3D printer, here’s a quick recap: the MMU3 is our solution for printing with up to 5 colors (filaments) at the same time. This optional add-on allows you to create beautiful, colorful objects quickly, easily, and with a minimum amount of waste. In fact, the MMU3 is an incredibly material-efficient solution, surpassed only by the multi-tool Prusa XL. The MMU3 for CORE One comes with a 0.4mm brass nozzle to replace the high-flow nozzle in the Nextruder for even better material efficiency.

We have developed a highly optimized and fast filament switching process in which only a very small amount of leftover filament needs to be purged into a mostly hollow “wipe tower” – a compact block at the edge of the print bed. With this solution, you don’t have to worry about hills of wasted plastic piling up next to your printer. Another great benefit of the MMU3’s setup with the spoolholders next to the printer is the fact that you can use spools of any size to achieve even longer and more complex prints.

PrusaSlicer and the brand new EasyPrint are fully equipped with many tools not only for slicing colorful objects, but also for turning single-color objects into multi-colored ones. With virtual brushes and smart fill tools, you’ll turn any grey object into a colorful print in no time. We also ported material interlocking into our slicer, so the resulting objects are sturdy and solid, and they won’t fall apart in your hands after a while.

You can find many examples of the MMU3’s power and reliability on Reddit and other social media sites, where users often share large, beautiful prints finished without any interventions.

So, let’s take a look at the options for the CORE One!

MMU3 Lite Conversion Kit – As streamlined as possible

First of all, we finished a lightweight version of the MMU3 for the CORE One called MMU3 Lite. It’s the MMU3 mounted on top of the Prusa CORE One with the top panel removed.

With the top panel removed, the CORE One is no longer a fully enclosed printer – which still works great with PLA and PETG. Plus, it’s totally possible to design and print a custom cover, so we imagine that there will be community-made top panels available pretty soon. And the price is definitely an advantage.

The Lite version is an upgrade (a conversion), so it does not include the MMU3 unit itself. It is essentially a small pack of additional parts that allows you to quickly move the MMU3 to the CORE One from your MK4/S with as little hassle as possible. This version is for those who already have the CORE One at home, but also the MK4/S with the MMU3. Please note that you will need to disassemble the Nextruder on the MK4S to salvage MMU3-specific parts and move them to the CORE One.

So, if you’re looking for a way to transfer your existing MMU3 setup to the CORE One, the Lite Conversion Kit is a very cost-efficient solution.

MMU3 for the CORE One – Enclosed version

One of the major benefits of the CORE One is its enclosed chamber, and we wanted to keep it that way. And with the MMU3 unit battle-tested and fully compatible with the Nextruder (used in the MK3.9/MK4/MK4S and the CORE One), it didn’t make much sense to reinvent the wheel.

We researched ways to integrate the MMU3 with the CORE One while keeping the enclosed chamber, and the MMU3 Enclosed Version is the result. I mentioned it in a recent video: it’s a simple, functional, and easy-to-install solution, and it retains the sliding grille on top of the printer that allows printing of PLA and PETG with the front door completely closed.

This version will become available in early June. The orders are already live, and you can see the store page on our website right here. We consider this version of the MMU3 the default version, which most users will choose. If you already have the MMU3, you can also get this version as an upgrade kit, containing only the parts necessary for the conversion from MK4/S – the upgrade kit includes the new top cover.

Enclosed versions list:
MMU3 Enclosed for the CORE One – Conversion Kit (does not include the MMU3 unit)
MMU3 Enclosed for the CORE One – Full Assembly Kit (includes MMU3, requires assembly)
MMU3 Enclosed for the CORE One – Assembled (includes assembled MMU3 unit) – coming soon

If you have a CORE One and want to expand it with the MMU3, get either the Full Assembly Kit or the Assembled version.

MMU3 – Community Version

And last but not least, we have something for everyone who is up for an awesome weekend project. During the development of the MMU3, we made several prototypes. And one particular design was really close to something our users often discussed online – all five spools neatly seated on top of the printer, everything nice and tidy. However, we have ultimately decided not to go this way; it’s a completely different kind of setup, and it makes more sense for us to pursue a similar concept in a next-gen solution.

Also, this version does not use the buffer – each of the spoolholders has space for retracted filament. This leads to a slightly decreased reliability, which is something we did not want to sacrifice in a commercial product. Last, but not least, printing this version will consume 4-5 spools of filament. You’ve been warned. 🙂

If you want to give it a try, you can download the files at Printables.com. Please keep in mind that you will need a special, longer cable to connect the MMU3 with the printer’s mainboard – you can order the cable in our e-shop. We expect to stock and start shipping it up by the end of June.

As I said, we really like this design and it would feel like a missed opportunity not to share it with you. This is why we decided to make these files public – so, this solution is endorsed by us (and comes from our office), but it’s not officially supported, mainly because it’s not polished to 100%. We’ve probably got it to a good 80-90% or so, and I’m betting our amazing community will quickly bridge that gap with their own clever tweaks – and probably take it even further!

Next Gen “MMU” in the Works

Now, I talked about it in the recent video, and I want to repeat it here, too, because I think it’s only fair to inform you about our future plans. We already have a new solution for printing with multiple filaments in the works. It will be something completely different, a complete re-imagination of the concept, which also means that the upgrade path from the MMU3 will be broken (so it’s not going to be an MMU4).

We’re in the early stages right now, so it’s safe to say that you won’t hear about the new thing for some time. We will, of course, inform you once there is anything to share.

Happy printing!