A teenager born without a right forearm due to a rare genetic condition has built himself a robotic prosthetic arm using Lego pieces.

Key points: David Aguilar unveiled his first Lego arm in November 2017 and is up to his fourth version

David Aguilar unveiled his first Lego arm in November 2017 and is up to his fourth version He wants to provide cheap, and even free, prosthetics for people missing limbs

He wants to provide cheap, and even free, prosthetics for people missing limbs He runs a YouTube page called Hand Solo

David Aguilar, 19, who studies bioengineering at the Universitat Internacional de Catalunya in Spain, is already using his fourth model of the colourful prosthetic and his dream is to design affordable robotic limbs for those who need them.

Once his favourite toys, the plastic bricks became the building material for Mr Aguilar's first, still very rudimentary, artificial arm at the age of nine, and each new version had more movement than the one before.

"As a child I was very nervous to be in front of other guys because I was different, but that didn't stop me believing in my dreams," he said.

"I wanted to … see myself in the mirror like I see other guys, with two hands."

He uses the artificial arm only occasionally and is self-sufficient without it, with all the versions on display in his room in the university residence on the outskirts of Barcelona.

In November 2017 Mr Aguilar, who uses Lego pieces provided by a friend, proudly displayed a fully functional red and yellow robotic arm, built when he was 18, bending it in the elbow joint and flexing the grabber.

The latest models are marked MK followed by the number — a tribute to comic book superhero Iron Man and his MK armour suits.

Each version improved on the last, with MK IV (left) the latest. ( Reuters: Albert Gea )

The MK II was a predominantly blue model built from a Lego plane set, including a motor, while MK III was created from a set for a piece of mining equipment.

In a presentation video on his YouTube channel that he runs under the nickname Hand Solo, the Andorran said his aim was to show people nothing is impossible and disability cannot stop them.

After graduating from university, he wants to create affordable prosthetic solutions for people who need them.

"I would try to give them a prosthetic, even if it's for free, to make them feel like a normal person, because what is normal, right?" he said.

Reuters