Born without part of his left arm, Porter had a traditional prosthetic when he was younger, but his mom Ryan told the The Augusta Chronicle that it was cumbersome for a growing boy.
"It didn't really move," she said. "So to a little kid, it was nothing but dead weight. He did a lot without it."
His new arm, though, is an improvement in every way.
Not only is it lighter and easier to move, it's also aesthetically modeled after the armor worn by the Imperial Stormtroopers in Star Wars.
John Peterson created the arm for Porter after coming across e-NABLE, an online community of people with 3D printers who work together to create prosthetics for those in need.
The group collaborates with professionals to create prosthetic designs, which are free to any individuals who might want to use them. (The Robohand that Porter wound up with was a collaboration between a prop maker in Washington and a carpenter in South Africa.)
Creating the prosthetics from plastic and keeping the designs open source means the price stays low: Porter's arm took about three months to make and cost approximately $300. That's much cheaper than the $9,000 a typical prosthetic hand would cost, Peterson said.
Porter's hand – officially designated the RIT Arm – has a clamp on it and a rail system to slide different attachments on and off. Once Peterson attached the arm, Porter figured out how to flex the fist and hold a cup.
"There's very few people who have these so you kind of have to figure it out on your own," Peterson noted. "Once he gets the arm, he might come up with all kinds of ideas [for new attachments]."
As Porter grows, the Robohand can also be adjusted to fit him.
Porter's new arm debuted at a "ceremony" at a movie theater with members of Georgia's 501st Legion, a group of people who cosplay as Stormtroopers. They presented Porter with his new arm and a custom-painted Stormtrooper helmet.
"Looking good, sir," Atlanta resident Melissa Barnes told Porter – who, as a commander, now outranks her. "I like the helmet."
Porter's grandfather, Bob Richards, watched Liam put his new arm through its paces with the 501st Garrison.
"That's something he is going to remember for the rest of his life," he said.