Robert Downey Jr. Presents Iron Man Arm to Boy, 7

Not only did Alex Pring, 7, recently receive an Iron Man-themed prosthetic arm: None other than Robert Downey Jr. presented it to him. Alex's bionic prosthetic limb was made by Limbitless Solutions, a nonprofit run by University of Central Florida students. The group's goal is to 3D-print affordable bionic limbs for kids (its appropriate URL: 3dhope.com), and this one is their first effort, the Washington Post reports. Using something called surface electromyography, electrical signals from the brain are communicated to the bionic arm, causing the hand to open and close. The awesome part: While a prosthetic typically clocks in around $40,000, the Iron Man arm cost less than $350 in materials; the fairly substantial research and development time were donated.

The arm itself was actually donated to Alex, who was born without most of his right arm, with team members contributing their "coffee money" to cover the materials cost. "Albert has made it so affordable," says "Tony Stark" in the now-viral video, referring to Limbitless founder Albert Manero. "I'm probably going to start farming out a lot of my tech work to Albert, too. I feel like he could cut the price point down on one of my suits, which right now is, I guess about, I don't know, a billion and a half dollars." (More Robert Downey Jr. stories.)