Free No account needed

MachineBlocks

Customize LEGO compatible bricks online and export print-optimized 3MF or STL

MachineBlocks is a free browser tool for custom and missing LEGO compatible parts. Free; no account or pricing on the site. Exports 3MF and STL. Last checked 26 September 2026.

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Opens machineblocks.com

At a glance

Price: Free; no account or pricing on the site.
Runs on: Browser
Exports: 3MF, STL
Multicolor: No, single color
Account: Not needed
Open source: No
Skill level: Easy: a few settings to tune
Best for: Custom and missing LEGO compatible parts
Selling prints: Not allowed The MachineBlocks license page says the core library is free for personal use under CC BY-NC-SA 4.0 and may not be used for commercial purposes. The maker told us by email (12 October 2026) that the current version is non-commercial; a later version may move to the Apache 2.0 license and allow commercial use, but that is not decided yet.
How we checked: Read the tool page and docs Examples library (site v0.9.21) lists 17 part families, from arches to Technic liftarms; the GitHub license is CC BY-NC-SA 4.0.
Checked by: Mike Janssen
Last checked: 26 September 2026

Open generator

Sources: MachineBlocks licence page, MachineBlocks licence (GitHub), MachineBlocks examples (checked 26 September 2026)

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What is MachineBlocks?

MachineBlocks is a toolkit for printing building blocks that fit with LEGO. On the website you pick a starting example, such as a classic brick, plate, tile, slope, arch, Technic beam or storage box, adjust its size and features in the online editor and download the model.

The bricks are shaped with 3D printing in mind rather than copied from molded parts, and a calibration tool tunes the fit of studs and tubes to your own printer and filament, which is the part most printed bricks get wrong. LEGO fits need about 0.1 mm precision, which most home printers do not reach out of the box, and some filaments, certain PLAs among them, shrink more than others, so calibrating gives a good clutch on any printer even when the model itself is exact. There are examples for text and icon bricks, base plates, containers and corner pieces. Models download as 3MF or STL.

Behind the web editor is an OpenSCAD library that advanced users can run locally, shared under a non-commercial Creative Commons license. It suits parents, LEGO fans and teachers who need missing sizes or custom parts, and it is not affiliated with the LEGO Group.