If this video doesn't lift your spirits today, I don't know what will. Actor Robert Downey Jr. (RDJ), who plays Iron Man in the "Iron Man" and "Avengers" movies, has partnered with a maker of bionic limbs to give one lucky 7-year-old an amazing new arm.

Alex, whom RDJ calls the "most dapper 7-year-old [he's] ever met," loves superheroes and riding his bike, and was born with a partially developed right arm. To give Alex a new arm, RDJ teamed with Albert Manero, a Fulbright scholar and doctoral student in mechanical engineering at the University of Central Florida who builds and donates low-cost 3D-printed bionic limbs to kids around the world through his volunteer group Limbitless Solutions.

The arm cost just $350 (about £235, AU$455) in materials to make, as noted by Microsoft's The Collective Project, which is featuring stories of students making positive changes for their communities. That makes it far cheaper than the $40,000 (about £26,900, AU$52,000) it traditionally costs to make such limbs.

Check out the video at the top of this post to see RDJ presenting a grinning Alex in a red bow tie with his new arm, and be sure to have a few tissues at the ready. Then click on the various links throughout this post to learn much more about this incredible project.