If you lose your hand in an accident, a prosthetic could cost well over £10,000. But 3D printing holds out the promise of making simple replacement hands available for far less.

In a closet-sized room in Tokyo's Akihabara electronics district, the founders of robotics startup Exiii pore over the designs for their latest prototype. It's a basic mechanical hand and forearm made from materials that only cost about £150. It's also open source.

The Exiii Hackberry, as it's called, has a flexible wrist, partially motorized fingers and low-cost parts such as an Arduino controller and a digital camera battery, all housed in a white 3D-printed plastic shell.

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