3D printed, LEGO-compatible parametric robot hand

PELA Robot Hand

3D Printed LEGO-compatible Parametric Robot Hand based on PELA Blocks

License: CC BY-NC-SA 4.0

This robot hand is a work in progress.

Open source design, Powered By Futurice


These open source designs are brought to you by Futurice and contributions from the community. Come work with the best.

The software needed is free and open source, OpenSCAD. You can probably learn it in less than an hour.


PELA Robot Hand

3D PELA Robot Hand

Fingers are attached to the plam by Technics connectors. Finger joints have 2 bearings inserted in bearing mounts and connected by a metal shaft. Finger movement is actuated by metal guitar string strung through guide holes top and bottom. Replacable, flexible skin with PELA connectors on the inside surface and touch sensitivity on the outside will be added (not shown).

Finger 1, Thumb, Print Layout

3D Finger 1, Thumb, Print Layout The thumb can bend double under the palm. End stops limit motion to 90 degrees.

Finger 2, Pointer, Print Layout

3D Finger 2, Pointer, Print Layout

Finger 3, Middle, Print Layout

3D Finger 3, Middle, Print Layout

Finger 4, Ring, Print Layout

3D Finger 4, Ring, Print Layout

Finger 5, Pinky, Print Layout

3D Finger 5, Pinky, Print Layout

Palm, Open Bottom

3D Palm, Open Bottom

Palm, Solid Bottom

3D Palm, Solid Bottom

Palm, Knobs Bottom

3D Palm, Knobs Bottom

Palm, Sockets Bottom

3D Palm, Sockets Bottom

Palm Cover, Knobs

3D Palm Cover, Knobs

Palm Cover, Sockets

3D Palm Cover, Sockets


If you prefer to avoid git, you can download the files instead.

  1. Download and unzip PELA Robot Hand
  2. Download and unzip PELA Blocks as a subdirectory (PELA-robot-hand\PELA-blocks)
  3. Calibrate the models to your printer/filament/slicer/preferences

Git Clone

  1. git lfs install and git clone --recurse-submodules
  2. cd PELA-robot-hand\PELA-parameteric-blocks and then git checkout master
  3. Calibrate the models to your printer/filament/slicer/preferences
  4. When PELA Blocks changes, backup your calibration files if needed, then either git submodule update --remote or cd into the submodule and git reset --hard origin/master and git pull

See also Advanced Setup


IMPORTANT: The STL models must be customized for your material, printer and slicer. First calibrate the PELA blocks for your printer to achieve a nice snap fit.

See also Advanced Calibration

Calibration File Backup

If you later update the PELA-blocks project to a newer version, you risk overwirting and loosing your calibration customizations. The simplest solution is to create a backup copy those settings.

  1. cd PELA-robot-hand/PELA-Blocks
  2. cp PELA-parameters.scad ../PELA-parameters-backup.scad
  3. cp PELA-print-parameters.scad ../PELA-print-parameters-backup.scad


Edit the OpenSCAD files to generate different views such as one finger at a time.

Be patient, have a nice meal and a coffee, the models are complex and render slowly.


License: CC BY-SA 4.0

Creative Commons Attribution-ShareAlike 4.0 International License

These designs are by PELA project contributors, not by the LEGO corporation. They are compatible with LEGO and similar blocks available from multiple manufacturers and online projects. The associated patents have expired. These designs are not identical to LEGO; they have been specially modified for easy 3D printing and offered in the spirit of open source collaborative innovation.

If what you want is available as injection moulded plastic, buy it for the higher quality and durability. These model are helpful when you want something customized, a special color, an unusual material, and for replacement parts when you just can’t wait.


Collaboration and pull requests are welcome: Git Project ( Blog - Twitter )

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