Iron Man star Robert Downey Jr is not only a superhero onscreen, he also plays his part offscreen as well, in the eyes of a seven year old boy.

Otherwise known as Tony Stark, Downey donned his black suit presented a working bionic prostheses to seven year old Alex, who was born with a partially developed arm as shown in a video posted online last Thursday, according to CBS Los Angeles via Associated Press.

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Downey opened a pair of metal cases, which was marked Stark Industries.  The box revealed an Iron Man bionic arm and a smaller red and gold prosthetic arm for Alex.

Wearing a black shirt and red bow tie, Alex proudly acknowledges in a video footage that he finally met and exchanged conversations with Iron man, who he also calls 'Robert'.

Alex also received an 'Optimus Prime' version of his limb last Christmas before receiving his new Iron Man bionic arm.

The bionic arm was made by an engineering student named Albert Manero, who builds and donates 3D printed bionic limbs to children around the world.

Marnero worked with Alex's family to create the digital arm in perfection that in such a way Alex can move by flexing his biceps.

Each limb constructed costs around $350 in production costs. The 3D printer used is in the university lab and it takes 30-50 hours to create a limb.

Marnero's company, Limbitless Solutions, aims to put 3D printers in embassies around the world so that children from the countries who are not advanced in medicine can benefit from its designs. Donations for Limbitless solutions can be made via their Paypal account.

TagsRobert Downey Jr., Bionic Arm, seven year old boy