For her graduate work at the Royal College of Art, Dani Clode created a wearable third thumb that can help its user carry more objects, squeeze lemons or play complex chords on the guitar.

The Third Thumb is a motorised, controllable extra digit, designed for anyone who wants to extend their natural abilities.

A student of the school's product design masters, Clode created the device as a way to challenge conventional ideas about prosthetics – usually thought of as devices only for people with disabilities.

"The origin of the word 'prosthesis' meant 'to add, put onto', so not to fix or replace, but to extend," said Clode. "The Third Thumb is inspired by this word origin, exploring human augmentation and aiming to reframe prosthetics as extensions of the body."

"It is part tool, part experience, and part self-expression," she added. "It instigates necessary conversation about the definition of 'ability'."

The Third Thumb is controlled by the movement of the wearer's feet, via pressure sensors embedded in their shoes.

Clode chose this method of control to exploit existing connections between our hands and feet, which we regularly employ together when driving a car, operating a sewing machine or playing a piano.

To emulate the dynamic range of movement provided by our natural thumbs, Clode made the digit out of a 3D-printed flexible plastic filament called Ninjaflex. Two motors pull the digit in various directions to make it bend at its three hinges.

A cover, also 3D-printed but from a more rigid resin, slips over the hand and wrist to hold the device in place. It is connected to the thumb through a cable system Clode describes as being similar to a bike brake.

She envisages using 3D-printing in future iterations of the design, as it allows for the design to be customised to fit different hand sizes.

Clode is originally from New Zealand and completed her undergraduate degree at Victoria University in Wellington before moving to London to study at the RCA.

This year's RCA graduate exhibition ran from 24 June to 2 July at the school's Kensington campus. Other showcased projects included a vertical transportation system that allows people to cycle up buildings, and a set of wobbly silicone plates that add a new dimension to the dining experience.