While we wait for Avengers: Age of Ultron to hit theaters, Robert Downey Jr. "reprised" his role as Tony Stark to help a young boy with an underdeveloped arm. The actor teamed up with Microsoft's The Collective Project and college student Albert Manero, who builds low-cost 3D-printed bionic arms, to deliver an Iron Man-inspired bionic arm to a 7-year-old boy named Alex Pring, who was born with a partially-developed right arm. Here's what Robert Downey Jr. had to say on his Facebook page earlier today.

"Had the absolute privilege of presenting a brand spanking new 3D-printed bionic Iron Man arm to Alex, the most dapper 7-year-old I've ever met. Special thanks to Albert Manero, OneNote, and #CollectiveProject for their work making artificial limbs like this more affordable for families with kids who want to show the playground how badass they are. Check out Facebook.com/LimbitlessSolutions to learn more about this incredible project. #goodcause"

The actor also posted a touching two-minute video where he is seen wearing his own Iron Man arm alongside Alex, including a memorable "fist bump." Take a look at the video below, along with photos from the actor's Twitter page, and CLICK HERE to learn more about Albert Manero and Limbitless Solutions.