Prusa CORE MINI

Overview

Prusa CORE MINI is a CoreXY conversion project for the Original Prusa MINI / MINI+.

The project transforms the original cantilever-style MINI into a compact CoreXY machine while reusing many of its original components. The frame, motion system, and print head assembly were redesigned around the original hardware.

Rather than replacing the original electronics with a different control system, CORE MINI retains the original Buddy board and LCD and runs on a modified version of the Prusa Buddy Firmware.

Specifications

Features

• CoreXY motion system, converted from the original cantilever Cartesian design

• Direct-drive extruder, converted from the original Bowden setup

• Reuses many original Prusa MINI / MINI+ components

• Modified Prusa Buddy Firmware with CoreXY support

• Full STEP assembly available for modification and further development

Project Status

Prusa CORE MINI is currently under active development.

The printer has been assembled and successfully tested for printing, but the design and documentation are not yet finalized. This initial release focuses on making the STEP assembly available for those interested in exploring or modifying the design.

The BOM, wiring information, assembly instructions, and other documentation are still being prepared and will be added in future updates.

Feedback and suggestions are always welcome as the project continues to evolve.

Demonstration

Prusa CORE MINI was demonstrated at Japan RepRap Festival 2026 (JRRF2026). These short videos show the prototype in operation.

3D models featured in the videos:

• "3DBenchy" by CreativeTools, https://www.3dbenchy.com/

• "ColorMix Chameleon" by Prusa Research, printables.com/model/1734124-colormix-chameleon/

Known Issues

The current design has several known issues that may be addressed in future revisions:

• The MINI-heatbed-cable-cover-top interferes with the 5003 fan duct.

• Installation and adjustment of the lower belts and pulleys are more difficult than intended.

• Some parts and dimensions may change as the design continues to be refined.

Future Work

Several future developments are being considered for Prusa CORE MINI:

• Complete the enclosure with top, side, and front panels.

• Upgrade the direct-drive extruder using internal drive components from the Bondtech IFS Extruder for Prusa MINI: https://www.bondtech.se/product/ifs-extruder-for-prusa-mini/

• Explore a return to a Bowden-style extruder, similar to the original MINI / MINI+, to reduce printhead weight.

• Add support for non-planar printing using E3D Revo Belt / Non-Planar nozzles and a compatible Revo coldside:
  https://e3d-online.com/products/revo-belt-nozzles
  https://e3d-online.com/products/revo-prusa-coldside-kits?variant=41629420388411

• Reduce the overall printer footprint while maintaining the current build volume.

• Review and redesign larger printed parts so that all components can be printed within the 180 × 180 mm build area of an Original Prusa MINI / MINI+.

• Explore incorporating features introduced with Prusa Gen 2 machines, including selectable 2GT / 1.5GT belt configurations and a nozzle cleaner.
  https://blog.prusa3d.com/better-prints-easier-use-prusa-xl-core-one-l-and-core-one-gen-2-our-big-product-update_137539/

Bill of Materials

This is a preliminary BOM and will be expanded and updated as the project develops. Prusa CORE MINI reuses many components from the Original Prusa MINI / MINI+, along with additional aluminum extrusions, motion components, fasteners, and printed parts.

Some purchase links in this BOM are affiliate links. If you purchase through these links, I may receive a small commission, which helps support further development and future modifications of this project.

Print Settings

The provided .3mf files were created and configured in PrusaSlicer, using the Prusa CORE One (MMU3) 0.4 mm nozzle profiles as starting points.

Most structural parts can be printed in PETG. However, parts located near heat sources, particularly 4006 and 5003, are recommended to be printed in a more heat-resistant material such as ABS, ASA, or PC-CF.

Please adjust the print settings as necessary for your printer, material, and environment.

Firmware

Prusa CORE MINI uses a modified version of the official Prusa Buddy Firmware to support the CoreXY configuration while retaining the original Buddy board and LCD.

Source code and precompiled .bbf firmware are available on GitHub:

https://github.com/hiroloquy/Prusa-CORE-MINI-Firmware

Please check the GitHub repository and Releases page for the latest firmware and installation information.

References

The following open-source projects and designs were used or referenced during the development of Prusa CORE MINI:

1. Original Prusa MINI — Prusa Research
   The primary basis of this project. Original MINI hardware and CAD data were extensively reused and modified to redesign the printer around a compact CoreXY architecture.
   https://github.com/prusa3d/Original-Prusa-MINI

2. Prusa CORE One — Prusa Research
   The official CAD model was referenced during the mechanical design process, particularly for the overall CoreXY layout, component arrangement, and packaging.
   https://www.printables.com/model/1520471-prusa-core-one-full-cad-assembly

3. Prusa-Firmware-Buddy — Prusa Research
   Used as the basis for the modified firmware developed for Prusa CORE MINI, enabling the original Buddy board to operate with the modified CoreXY configuration.
   https://github.com/prusa3d/Prusa-Firmware-Buddy

4. Prusa Mini & Mini+ USB-Plug and Power Switch Frontplates — ChefBenni
   The original CAD design was modified and integrated into the CORE MINI frame.
   https://www.printables.com/model/37430-prusa-mini-mini-usb-plug-and-power-switch-frontpla

5. Prusa Mini Displaybox Cover for Prusa Mini & Mini+ USB-Plug and Power Switch Frontplates — handro
   The original CAD design was modified and adapted for the display assembly used in CORE MINI.
   https://www.printables.com/model/388535-prusa-mini-displaybox-cover-for-prusa-mini-mini-us

6. Magpie — Wilkes
   Referenced when developing the Z-axis mechanism, particularly the belt-synchronized leadscrew arrangement, belt routing, and tensioning concept.
   https://github.com/magpie-printer/magpie

7. Prusa MINI CoreXY — SE
   Referenced as an earlier example of converting the Prusa MINI to CoreXY while retaining the original Prusa firmware. Its bed support arrangement was also considered when developing the three-point bed support used in CORE MINI.
   https://www.printables.com/model/681983-prusa-mini-corexy

8. LCD Ribbon Cable Clip for 2020 Extrusion — ijmwi
   The original model was resized and used for routing the USB, power switch and LCD ribbon cables along the aluminum extrusion.
   https://www.printables.com/model/449008-lcd-ribbon-cable-clip-for-2020-extrusion

Changelog

• v0.1.0

  • Initial public release

  • STEP assembly released

  • Modified Buddy Firmware available separately on GitHub