Ironman has become latest superhero to step out of the big screen to do some good in the ordinary world. Following on the heels of Chris Evans and Chris Pratt donning the costumes of Captain America and Star Lord to visit sick children at the Seattle Children’s Hospital, Robert Downey Jr. teamed up with a nonprofit to deliver an Ironman-themed prosthetic limb to a 7-year-old boy with a partially developed right arm.

The encounter was organized by a group called Limbitless, which was founded last May by Fulbright scholar and University of Central Florida engineer Albert Manero. The organization is dedicated to producing affordable artificial limbs for the children who need them. “My parents always encouraged me to use my education to help others and to dream big dreams,” said Manero. “Now I want to inspire others to help engineer hope for the world.”

Downey’s visit to young Alex Pring was filmed by Microsoft and posted as a short video on YouTube. The 7-year-old is clearly excited and nervous to be greeted by his hero. When asked, “Do you know who that is?” Pring replies, “Ironman!” and an equally excited Downey punches his fist into the air.

In the video, the movie star and the boy compare mechanical arms, and Downey jokes, “I think yours is a little bit more right than mine, because at least your light works.”

Prosthetic limbs can often cost as much as $40,000, limiting their availability to those who need them most. However, using innovative technology such as 3D printing, Manero’s group was able to create Pring’s arm using just $350 worth of materials, which they raised by pooling their “coffee money.”

“We were all bound to the belief that no one should profit from a child in need of an arm,” said Manero.