Prusa’s MMU3 Gets a Farewell Firmware Boost, Shifts to DIY Path for Core One L

According to a blog post detailing the changes, the update drops swap times from approximately 52 seconds to around 42, a roughly 20% improvement. It’s also, as the company openly acknowledges, the last major one the device will receive.

The update – printer firmware 6.5.3 paired with MMU firmware 3.0.4 – achieves its gains through parallel idler operations (the extruder no longer waits for the MMU to disengage before pushing filament), predictive idler staging during unloads, and a refined pressure-relief step that allows faster retraction speeds.

Prusa gives the example of a detailed model with 2,200 filament changes saving five and a half hours, and a moderately complex five-color print with 400 changes saving roughly an hour. Across a production batch of 25 small items, the savings add up further. The company quotes a range of two to six hours saved depending on model complexity, noting these figures are “rather conservative”. If you know your machine is well maintained and you’re comfortable pushing things, there’s headroom to go faster.

It is not a small improvement for a system where every color change demands a full unload, load, and purge cycle. For the likely thousands of MMU3 units already in the field – the device has been available since mid-2023 – it’s a surprisingly generous performance gain at no cost. The update covers the MK4S, MK3.9, MK3.5, and Core One/One+ platforms.

Another usability bump for the MMU comes in the addition of a “Preload All” feature that lets you load all filament slots with the same material type in one step, rather than clicking through each slot individually. Other changes in the firmware include a new LED lighting status effect for Core One L users and a bugfix that addresses improperly swapped axis values for input shaping on the company’s CoreXY style machines.

Prusa frames 3.0.4 as the MMU3’s final significant firmware update. The company says the unit will remain on sale and supported, but development priority is shifting to the INDX toolchanger upgrade. For existing owners not planning to jump to the new platform, firmware 3.0.4 is probably as good as the MMU3 is going to get.

The INDX, created by Bondtech and co-developed by Prusa for the Core One series, takes a fundamentally different approach: instead of swapping filaments through a single nozzle, it swaps passive toolheads – lightweight nozzle assemblies that each retain their own filament path. This eliminates the unload/load/purge cycle entirely. The limited-run Founders Edition INDX is expected to ship imminently, if not already, while the general release is anticipated to follow in Q2.