WATCH: 'Iron Man' presents kid with real bionic arm 

 Check out this heartwarming video of Hollywood actor Robert Downey Jr. (RDJ), who plays Iron Man in various films of the Marvel Cinematic Universe, presenting a 3D-printed bionic arm to a handicapped 7-year-old kid.

Alex, whom RDJ refers to as the "most dapper" 7-year-old he has ever met, was born with a partially developed right arm. He also happens to love superheroes and riding his bike.
So imagine his surprise when he was greeted by RDJ dressed as the "leading bionics expert" Tony Stark inside a hotel room.

"Had the absolute privilege of presenting a brand spanking new 3D-printed bionic Iron Man arm to Alex," wrote RDJ on his Facebook page.

The new arm was built and designed by Albert Manero, founder of volunteer group Limbitless Solutions. The doctoral student aims to make 3D-printed bionic limbs affordable "for families with kids who want to show the playground how badass they are."

The arm costs $350 in materials to make, according to Microsoft's The Collective Project. A report from tech website CNET noted that is "far cheaper than the $40,000 it traditionally costs to make such limbs."

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