It’s always nice when Hollywood’s most famous faces prove they too have a heart. And Robert Downey Jr. is one of the actors who did this on several occasions. Alex was born with a partially developed arm. The 7-year-old boy also loves superheroes, and that’s where the famous actor from Iron Man comes in. He surprised the boy with a brand new bionic 3D printed arm, at no cost to the family. The arm was designed by Albert Manero, a college student who builds and donates low-cost, 3D-printed bionic limbs to kids around the world. Amazing!