The Original Prusa MK4S is Prusa Research's flagship open-source FDM 3D printer, fully assembled and ready to print out of the box. The MK4S builds on the proven MK4 platform with an upgraded 360° cooling system that significantly improves overhang performance and surface quality on complex geometry. With a 250×210×220 mm build volume, the Nextruder direct drive extruder, and Input Shaper technology enabled from the factory, the MK4S delivers consistent high-quality prints across a wide range of materials without manual calibration.

Key Specifications

Print technology	FDM / FFF — Cartesian (bed-slinger)
Build volume	250 × 210 × 220 mm
Max nozzle temperature	290°C
Max bed temperature	120°C
Layer resolution	0.05–0.30 mm
Extruder	Nextruder — direct drive, load cell-based auto-levelling
Cooling	360° part cooling (MK4S upgrade)
Bed surface	Removable spring steel sheet (magnetic PEI)
Input Shaper	Yes — enabled from factory
Connectivity	Ethernet, Wi-Fi, USB
Remote monitoring	Prusa Connect
Firmware	Open-source (Prusa Buddy)
Assembly	Fully assembled

MK4S vs MK4 — What Changed

The key difference between the MK4S and its predecessor is the 360° cooling system. The original MK4 used single-direction part cooling, which limited overhang angles and required careful orientation of complex parts. The MK4S's 360° airflow wraps cooling air around the print from all directions simultaneously — improving overhangs, reducing stringing, and allowing more aggressive print speeds on detailed geometry without support degradation. Existing MK4 owners can upgrade to MK4S specification with the cooling upgrade kit.

Nextruder — Auto-Levelling Without Manual Z Offset

The Nextruder uses a load cell sensor to detect bed contact during first-layer calibration. Rather than relying on a probe offset (which needs manual tuning), the extruder itself detects the nozzle touching the bed and calibrates from that direct measurement. This means first layers are consistently correct from the first print on a new surface — no Live Adjust Z hunting required. The system compensates automatically when switching between textured and smooth spring steel sheets.

Material Compatibility

• Standard: PLA, PETG, ASA, ABS, HIPS
• Flexible: TPU, TPE (direct drive handles flexible filaments well)
• Engineering: PC Blend, PA-11 Nylon, PA-12 Nylon, PA-CF
• Composite: Carbon-fibre-filled, glass-fibre-filled, metal-filled (hardened nozzle required)
• High-temp: PC, CPE — up to 290°C nozzle and 120°C bed

Open Source and Ecosystem

All Prusa hardware design files and firmware are open source. The MK4S is compatible with PrusaSlicer (free, actively developed by Prusa Research) as well as OrcaSlicer and other community slicers. Prusa Connect enables remote print monitoring, camera integration, and print farm management from a browser or mobile device.

Who It's For

• Makers and hobbyists who want a reliable workhorse printer with no-fuss operation and excellent community support
• Designers and engineers using PLA/PETG for prototyping and functional parts
• Schools and educational labs needing a safe, well-documented, fully supported machine
• Print farm operators — the MK4S's reliability, remote management, and fast print speeds make it a proven farm platform

Available from Eolas Prints

Eolas Prints is an official Prusa Research reseller based in Cantabria, Spain. EU warranty, Spanish-language support, and fast shipping across Europe included.