We're open-sourcing "The Amazing Hand", a fully 3D printed robotic hand for less than $200 ✌️✌️✌️

Context

High-performance humanoid hands usually come with two painful trade-offs: sky-high prices and bulky, forearm-mounted actuators. Our Amazing Hand project solves both problems by packing eight degrees of freedom (DOF) into a fully self-contained, 3D-printed hand that costs less than €200 in off-the-shelf parts.

The main inspiration for this project comes from the "ILDA hand" research project which describes an anthropomorphic hand with linear actuators Kim, U., Jung, D., Jeong, H. et al. 2021.

ILDA Hand mechanism from https://doi.org/10.1038/s41467-021-27261-0

A few weeks ago, we released PincOpen, an open-source and low-cost parallel finger gripper.

Pursuing our commitment to open source AI and robotics, we are releasing a robot hand that we call "Amazing Hand", which simplifies the ILDA hand concept in order to lower the entry cost to be able to experiment with anthropomorphic hand.

"Amazing Hand" key points :

• 4-finger hand with 2 dofs per finger (=8 dofs hand)
• Dual hobby-grade servo motors per finger (flexion/extension & abduction/adduction via differential motion)
• Rigid "bones" + soft TPU shells for object-friendly contact
• Fully 3D printable
• 400g weight
• Cost < 200€

How it works

Each finger is actuated by 2 motors in parallel. Flexion/Extension and Abduction/Adduction can be achieved depending on the differential motion of the motors.

A mechanical linkage synchronizes proximal and distal joints, simplifying control without sacrificing range. 2 ball joints linkage allow to drive the proximal motion through actuators horn without the use of any cable. The finger structure is rigid, but is covered by 2 flexible shells which help to have friendly contact with them.

The range of motion of each finger in combination with placement on the hand allows to have an opposable thumb with the index finger (only).

Note that the palm is also a flexible part, to ease prehensile tasks without damaging objects.

Several possible patterns (and much more):

Right now the wrist interface of the "Amazing Hand" fits with the Reachy2 robot, because one of the goals of this project is to explore the hand capabilities on a real robot. Reachy2 is obviously a good candidate with its 7-DOF arm. But don't panic if you want to use it on another robot, CAD files are open source and easily customizable !

Advanced Hand tracking demo

There is also a hand tracking project based on a simple webcam to drive finger motion according to your own hand:

The inverse kinematics for this kind of mechanism is not trivial. We used a QP method with the Mink library and provide some example programs.

Ready to build?

This project is fully Open Source. BOM, 3D files, 3D-printed guide, assembly guide and basic demo programs are available on github: https://github.com/pollen-robotics/AmazingHand

Hack It, Fork It, Make It Yours

Because every CAD, firmware, and control file sits on GitHub under an open-source license, you can:

• Add a fifth finger (accepting extra thickness if needed).

• Remix finger geometry for custom human-like proportions.

• Swap the wrist mount for any robot arm.

• Embed fingertip sensors—Hall-effect, capacitive, vision, you name it.

Jump in, fork away, and help us build an even more Amazing Hand! ✌️✌️✌️