Adaptation of MMU3 Cassette Compatible Buffer for Prusa CORE One +

Adaptation of MMU3 Cassette Compatible Buffer for Prusa CORE One +

UPDATE: 8. August 2026 made Automatic Cassettes available for the buffer

After trying countless filament retraction systems (own designs and available on printables), I found that none of them worked flawlessly with all filament types, that can be used with the C1/C1+. Therefore, I reverted to the solution that had already worked perfectly on the MK4S.

It now flawlessly supports filament retraction from the MMU3 up to 950 mm !

No access will be obstructed by the Buffer, and it can be removed in a minute with four screws if necessary.

This remix contains exclusively a third (middle) buffer section and the mounting brackets for attaching it to the C1 or C1+ in four selectable positions.

Thanks to the full colored CAD model of vmLOGIC it was easy to model this remix in four variations and present nice pictures.

For the base buffer system, R4 cassette and loading aid use the following recommended links: 

Parts to print for mounting option:

• All directions: Cassette Compatible Buffer middle part

• Left Back side, pointing left: Top Mount LBl, Bottom Support LBl-RBb

• Left Back side, pointing back: Top Mount LBb, Bottom Support RBr-LBb

• Right Back side, pointing back: Top Mount RBb, Bottom Support LBl-RBb

• Right Back side, pointing right: Top Mount RBr, Bottom Support RBr-LBb

Printing recommendation:

• Filament PETG

• 0.4 Nozzle

• 0.2mm Structural

• 15 % Infill

• no supports

Assembly instructions:

• Add the third (middle) section to the buffer using four M3x8 SHCS screws.

• Attach the buffer top mount to the desired location: First remove the torx screw, then use a M3x10 SHCS screw to attach the buffer top mount.  

• Attach the buffer bottom support vertical underneath the top mount: Remove the torx screw, use a M3x10 SHCS screw to attach the buffer bottom support.

• Take the 3-part buffer and set it on to the bottom support, move the top side into the mounting bracket, use the four M3x10 SHCS screws to fix the buffer to the mounting bracket.

• Insert the cassettes, attach the PTFE tubes 1-5 on each side, load filaments.

Cassette removal procedure:

To remove the cassettes there is a best practice process (see picture below):

1. Press one lever completly to the cassette wall

2. Lift the cassette on that side for about 10mm

3. Press the opposite lever completly to the cassette wall

4. Lift the cassette on that side for about 10mm

5. Now drag the cassette vertical out of the buffer