Original Prusa i3 MMU2S upgrade kit (for MK2.5 & MK3S/+)
Multi Material Upgrade 2S (MMU2S) is a brand new and improved version of the Multi Material Upgrade 2.0 - our unique multi-material addon, which enables your 3D printer to print with up to 5 colors at the same time. With an easier calibration process, a new filament sensor, and a standalone filament buffer, the MMU2S is more reliable than ever before.
This product is supplied as a kit - you must assemble it by yourself!
Please note, the assembly manual for the MMU2S upgrade kit is available in digital form only.
Note for MK3 users, you also need to purchase the MK3/S to MK3S+ upgrade kit with the MMU2S.
Multi Material Upgrade 2S (MMU2S) is a brand new and improved version of the Multi Material Upgrade 2.0. With an easier calibration process, a new filament sensor, and a standalone filament buffer, the MMU2S is more reliable than ever before.
WITH THE ORIGINAL PRUSA MMU2S WE ARE INTRODUCING:
NEW FILAMENT SENSOR
With the MMU2S we managed to sense not only that the filament is present, but that it actually reached the Bondtech gears. The filament sensor detects when the idler doors open a bit as the filament pushes Bondtechs apart. MMU2S is much more reliable regarding reloading filaments and the calibration process is also simplified.
FILAMENT BUFFER
The MMU2S comes with the filament buffer, a device designed to prevent filament tangling during loading / unloading process. The buffer allows you to position the five filament spools more freely and also saves valuable space on your desk.
THOROUGHLY TESTED
The testing process of the MMU2S took 2 months to finish, we used 20 printers and we printed 478 test blocks designed to test frequent switching of all five filaments. The total value of filament changes was nearly 600.000. More than 93 % of this prints were successfully completed.
Multi Material Upgrade 2S (MMU2S) is the second generation of our unique multi-material addon, which enables your Original Prusa i3 MK2.5S or MK3S/+ 3D printer to print with up to 5 filaments at the same time. Compared to MMU1, the new MMU2S went through a major revision, resulting in a simpler and more reliable design. The number of simultaneously supported filaments increased to a total of five, which enables the users to print even more complex and more colorful objects. MMU2S comes with a redesigned body and a new filament loading mechanism. Instead of the previous Bowden system, the new unit uses a direct-drive feed and a single PTFE tube to lead the selected filament to the extruder. The motorized selector head has a F.I.N.D.A filament sensor and a built-in blade, which prevents filament jamming. Read more about MMU2S in the announcement blog post at Prusaprinters.org and in this upgrade article.
SEE THE MMU2S IN ACTION!
Introducing MMU2S
How does MMU2S work?
MAIN FEATURES
The most significant new features of Original Prusa i3 MMU2S
COMPLETELY REDESIGNED
MMU2S has a brand new body with a rotating pulley barrel and a single extruder motor. Load up to 5 filaments and the selector head with a filament-cutting blade will take care of automatic loading and unloading.
FIVE MATERIALS
The second generation of our Multi Material Upgrade supports up to 5 filaments loaded at the same time. Apart from usual materials like ABS, PETG or PLA, the MMU2S also works great with soluble supports (BVOH or PVA).
DIRECT DRIVE
We have replaced the previous generation's Bowden system with a new direct-drive mechanism. This change is a major step forward in making the filament loading process more reliable and less prone to jamming.
F.I.N.D.A FILAMENT SENSOR
Meet F.I.N.D.A! It's essentialy a repurposed P.I.N.D.A probe, which now serves as a filament sensor. It works on a mechanical basis - the string of filament lifts a small stainless steel ball and F.I.N.D.A detects its proximity.
WIPE INTO INFILL / OBJECT
Our slicing software Slic3r PE comes with full MMU2S support and a set of useful features, such as Smart wipe tower, Wipe into infill or Wipe into object. These features help you save time and filament.
FILAMENT BUFFER INCLUDED
The MMU2S comes with the Filament Buffer, a device designed to prevent filament tangling during loading / unloading process. The buffer allows you to position the five filament spools more freely and also saves valuable space on your desk.
FULL FEATURES LIST
MULTI MATERIAL UPGRADE 2S FEATURES
COMPATIBILITY INFORMATION
Printer Compatibility: Material Compatibility:
Reviews
The Seller does not verify whether the published reviews come from consumers who have actually used or purchased the products or digital content or service. Reviews are provided by registered PRUSA ACCOUNT users.
Using the MMU2S is surprisingly simple. The only things to "calibrate" are the FINDA up top and the moved IR-Sensor on the extruder, but both were very easy to adjust.The only downside I can list was during the build: The holes in the printed parts to slide the square nuts in were almost all not free -> needed to clear them out (I used a dremel) and the attachment of the PFTE tubes out of the MMU was a hassle (there are upgraded print files online from the community)
Very happy with the mmu2s on my 10th year anniversary i3.At first I had a problem with loading the filament. The IR sensor tower was flickering so when I loaded the filament it went into the hotend but then it was retracted out of it. This was happening all the time. After I readjusted the place of the tower with the 1.5 mm allen tool, the printer is working fine with the mmu2s on the test print with 104 colour switches. So double check your sensors before you start using it!

TLDR: Great upgrade! You need to be detailed orientated, or mechanically experienced, or have a friend over to help. Be aware that the buffer needs additional space, I missed that (my fault) but there is a great community with mods to make it all work. After wanting to print multi-color prints for over a year, I jumped into this without fully reading about all the parts for this upgrade. I would have still made the purchase, I wasn't prepared to need to modify the enclosure to fit all the spools and buff. Luckily there is a great mod on https://printables.com that offered hanging solutions for both spools and the buffer. The hanging buffer mod makes it easy to load new filament (just make sure you have room behind it to let it swing). I never loaded the buffer as described since I chose to mod before restarting printing. Setting up the parts wasn't too hard, I just had to follow the steps and read ahead. I followed all the steps as written until I had to load the buffer. I realized I had to hang it and so I had to disassemble the buffer partly to install it to hang. I went slow and double checked all the fittings with the upgrade taking about 6 to 8 hours (I did it over several days so I don't know the exact time). For a few of the clearings (holes), I used a drill bit to clean out the path (I expect this since the parts are 3d printed). The drill bit had a hex end that fit into a multi-head screwdriver. It make installing the pins easier and I didn't have to use as much force to install some parts.
Downloads
- MMU2S printable parts333 kB