That 7-year-old Liam Porter, who was born without part of his left arm, got fitted for a working prosthetic last weekend is sweet enough—but that it was a Star Wars Stormtrooper arm 3D-printed especially for him makes it a-mazing.

The arm was presented to Liam on Saturday afternoon in his hometown of Augusta, Georgia, when a group of Imperial Stormtroopers (actually members of the 501st Garrison, a group of diehard Star Wars fans) surprised him and escorted him to a local movie theater’s party room where his family and friends watched as he was fitted him with the new arm. Amid giggles, Liam summed it up in one word: "Cool."

RELATED: 6 Medical Breakthroughs That Matter

According to the Augusta Chronicle, designer John Peterson was inspired to make the arm when he stumbled upon E-nable, an online group of professionals who design prosthetics that can be 3-D printed for people who need them, but can't afford it. Printing a prosthetic arm from open-source designs can cost as little as $50 versus the $9,000 for a typical prosthesis, Peterson said. Plus, 3-D printed prosthetics are great for kids because they can be adjusted and re-created as the owner grows.

The design for the arm Porter got, called the RIT arm, took about three months and cost about $300, mainly because the original design was for a right arm, Peterson added.

Porter's mom, Ryan, told the Augusta Chronicle that his old prosthetic wasn’t very helpful because it didn’t really move and was “nothing but dead weight.” His Stormtrooper arm is already an improvement, not just in style but in function. In the video, Porter is shown picking up a cup for the first time. Check it out:

RELATED: Watch Bill Gates Drink Water That Had Been Poop Just Moments Before