Prusa Core One+ kit build

I ordered the Prusa Core One+ as a kit on 12 May 2026 and built it in seven sessions. I filmed every session, and the build was streamed live on the old version of this site.

Build stream

Build log

Date	Session	What got done
12 May 2026	Order	Kit ordered from Prusa Research.
28 May 2026	S1, base	Unboxed and sorted the hardware. Built the bottom frame, bottom plate, Z stepper mounts and anti-vibration feet.
2 Jun 2026	S2, electronics	Rear frame profiles, 24V PSU, xBuddy board box, Wi-Fi module, chamber fans and the main wiring loom.
9 Jun 2026	S3, heatbed	Wired the heatbed, threaded the bed carriage onto the Z rods with the brass nuts, added the RGB LED bar.
12 Jun 2026	S4, CoreXY	Linear X rail, Y rods, both steppers, belts tensioned, front LED bar and door sensor.
16 Jun 2026	S5, Nextruder	Planetary gearbox, idler lever, thermistor, LoveBoard, fans and the Prusa hotend.
18 Jun 2026	S6, bodywork	Front and top frame, filament sensor, NFC coil, back covers and handles.
21 Jun 2026	S7, panels	Acrylic lid and sides, xLCD, glass door. Flashed firmware, ran the wizard and the first print.

Calibration

After flashing the firmware, the setup wizard tests the door sensor, calibrates the loadcell, aligns the Nextruder and checks the filament sensor. Session 7 ended with the first test print.

MMU3

After the printer was stable I added the MMU3 for five-colour prints. The build has six parts: idler body, selector, pulley body, spool holders and buffer, a Nextruder modification, and calibration of the sensors and PTFE length.

Two things helped with feeding:

Use 2.5 mm ID PTFE tube instead of 2.0 mm for the long runs from the spool shelf. It cuts drag and slipping during retractions.
Keep every bend in the tube wider than a 10 cm radius between the spool deck and the selector.

The Core One upgrades page lists the printed mods I added after the build.

Build stream

Build log

Calibration

MMU3

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Specs