K’nex is like the misunderstood stepchild in the construction toy family. Unfairly compared to LEGO and Mega Bloks—and categorized alongside them—K’nex really is a whole different thing, though some recent licensed sets with Lego-ish minifigs have blurred the lines a bit. Lego and its imitators, in the hands of experts, are primarily about architecture and design; K’nex is about engineering. And the individual known on YouTube as Shadowman is a masterful K’nex engineer, having used the plastic connection toy to build coin-sorters, card-shufflers, and a skee-ball machine.

But perhaps none are as impressive as the Citadel, which we first saw thanks to Laughing Squid: it’s an eight-foot tall contraption that took three years to make. Plastic balls are elevated to the top by a lift, and make their way down 17 different possible paths, where the encounter pendulums, carousels, loop inversions, centrifugal force cones, weight sensitive plates, and more route back to the bottom where they can start all over again. If you were a ball, this would be the best roller coaster ever. Since you’re not, it just makes for a hypnotic and compelling YouTube video.

Using some of the old-school K’nex figures (before the licensed ones got more LEGO-y), he’s even given the whole thing the feel of an operational factory, or theme-park ride, with staircases and controls for the tiny people to navigate the mechanical maze and ensure everything keeps running. Now, why they’d be making giant balls, we don’t know. Maybe they really, really like bubble gum. Or maybe they are just trying to entertain the race of giants who will stare at this video on their monitors, sufficiently distracted while the rest of the K’nex men take over the world. Hey, it’s plausible.

Should you ever tire of the video (unlikely), be sure to check out his gallery of stills at Flickr as well.

Is it time to give K’nex its long overdue props? Connect with us in comments below.

Images: Shadowman39/Flickr