Watch Iron Man hand-deliver a child's 3D-printed, bionic arm and try not tear up

First, Robert Downey Jr. continues to be one of the coolest people in the world.

Honored to present a bionic #IronMan arm to Alex through @MSOneNote’s #CollectiveProject. Check the bowtie. #dapper https://t.co/lhLG5g1RP8

— Robert Downey Jr (@RobertDowneyJr) March 12, 2015

Secondly, this video is the work of The Collective Project, and while the addition of Hollywood talent in the arm's presentation gives a ton of PR value, the work being done by Albert Manero and Limbitless Solutions is just as interesting. The group is making affordable, 3D-printed prosthetics for children ... and then giving away the plans so others can do the same.

Here's a quick bit of background from the Microsoft blog:

Limbitless’ first arm – for an active boy named Alex – cost less than $350 in materials, much cheaper than the $40,000 price tag of some prosthetics. But the team’s volunteers donated the arm for free, after pooling together their "coffee money."

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

That's some real-world Tony Stark action right there. Here's a closer look at the arm.

It's great that Robert Downey Jr. donated his time, but people like Manero are perfect evidence that superheroes really exist.