Read how it was made here at Black Ram Industries.
The Black Ram Hand was designed not to be a replacement for current prosthetic hands, but to be an assistive technology tool/platform for allowing someone to design and use their own specific manipulators for individual tasks specific to that person. This is in the same way that Robotic grippers and end-effectors are designed for a specific goal.
The Black Ram Hand is designed to help those with missing fingers or conditions such as Dupuytren's Contracture. It is wrist powered and requires that the wearer have enough palm to push against the device. It converts the rotation of the wrist into a linear sliding motion to activate the end gripper. When the wrist is bent down the slider pulls back, closing the hand. When the wrist is straightened the slider pushes forward and the hand opens.
The Gripper heads are removable so that the user can change them and reconfigure the device to suit their needs. I have created 2 Claw types, Tri-Claw (for picking up or catching objects) and Two-claw (for open shut grasping of objects). New claw or manipulator types can be attached with 2 screws on the hand piece. Within these you can add any flavor of gripper suitable. I have added a few grippers as extras for people to try. I recommend that you start with the Simple Claw to get the feel of the device before printing the other variants.
The multi-joint finger requires the user to tune the fingers. There is a sequence of loose and tight bolts that needs to be determined to allow for the correct articulation of the fingers when opening and closing. I recommend first using simple or pincer claws first as the multi-joint fingers take some tuning to get working correctly.
For the Full Assembly instructions Refer to Thingiverse:
To See it in action watch the attached youtube clips: