Open-Source 3D Printing: Where to Find Projects, Hardware, Firmware, and Communities

“Open source” in this hobby is three different legal piles that people mash together. A GPLv3 firmware, a CERN-OHL printer, and a CC-BY-NC STL are not the same permission.

What “open source” means in 3D printing

OSI’s OSD is about software. Hardware and model-host terms are extra homework. Always open the LICENSE file or the listing badge — do not trust a Discord nickname.

Firmware projects

• Klipper — host + MCU split, input shaping, macros. Docs and source: github.com/Klipper3d/klipper. Confirm the license file on the default branch (historically GPL).
• Marlin — widely shipped on consumer boards. github.com/MarlinFirmware/Marlin.
• RepRapFirmware — Duet-class controllers.

Flash only what your board documents. A random .bin is how you brick a weekend.

Open hardware/printer projects

• Voron Design — kits + self-source. CAD/STLs: github.com/VoronDesign. Read the current hardware license in that org (CERN-OHL family — verify the file, do not quote a year-old tweet).
• Rat Rig — V-core class documentation lives with their repos and manuals.
• Prusa publishes original i3-class hardware files; current products still have their own terms — check the repo you actually cloned.
• Legacy RepRap lineage is historical context, not a shopping list.

Build 100% to spec the first time (Voron’s own docs say this). Then fork.

Slicer/tooling projects

• PrusaSlicer (AGPL — read LICENSE)
• OrcaSlicer (fork lineage; check its LICENSE)
• SuperSlicer
• OpenSCAD / FreeCAD for models you can diff in git

Vendor studios (Bambu, Creality, etc.) may be closed even when they import open slicer code. Read that product’s license screen.

Model/design collaboration

Printables, MakerWorld, and GitHub all host files. For anything you will sell or rehost, the listing license wins. Start at the model directory and featured designers. Gridfinity’s community wiki (gridfinity.xyz) describes the original release as MIT — still verify the file you download.

Where version control fits

If the project has releases, issues, and a LICENSE, you can file a bug. A Google Drive ZIP with “vFinal2_reallyfinal” is not a community. Prefer git tags that match the printed revision stamped on the part.

How to evaluate whether a project is alive

Stars are vanity. Releases and answered issues are not.

How to contribute without coding

• Print a release candidate and file a photo + printer + material (not “doesn’t work”)
• Fix a typo in the docs PR
• Translate a page if the project asks
• Triage duplicates
• Donate via the project’s listed path — not a random “official” merch drop

Licensing basics and where to verify terms

1. Open the exact commit/tag you will build.
2. Open LICENSE / COPYING / the storefront badge.
3. If it is hardware, read whether private use, commercial production, and relicensing are allowed (CERN-OHL variants differ).
4. If it is a model, CC-NC usually blocks selling prints — but read that version.
5. When unsure, ask the author in writing or do not commercialize.

SPDX and choosealicense.com explain software licenses. They do not replace a hardware license text.

Community/project directory

We will not add a Discord because it emailed us. Suggest a living project with a license file.

Sources

• Klipper documentation
• Voron documentation
• Open Source Definition
• SPDX license list
• Project LICENSE files linked above (verify on the commit you use)