The hardest problem with any one-wheeled machine is keeping the machinery steady while everything around it spins. The maker tackled that head on with a counterweight layout: two weight bricks sit low in the core, and gravity holds the heavy middle stable while the wheel rolls around it. To me that seems like the smartest call in the whole design, since it is what lets a motorized single-wheeler stay upright at all.
Putting it together, the rolling rim is flexible tubing trimmed to size and run through Technic bricks that have axle holes, then covered by curved slope pieces with bracketed edge plates riding on a pair of round Technic wheel frames. The internal drive unit carries a battery box plus an infrared receiver. Two Power Functions M motors split the jobs: one turns the central axle fixed to the outer side discs to move the wheel, while the second slides the core sideways along a gear rack, making the machine lean and carve a turn.
The surface work stands out too. The tread is built from curved pieces in black and red, and the handheld infrared controller has two orange control dials. The maker demonstrates driving it with that controller, and the whole thing reads as a proper little vehicle rather than a bench test.
There is a stated purpose behind it as well: it began as a proof of concept aimed at a LEGO BB-8 droid model, and the maker presents it as a concept study toward a working droid in LEGO.
It is not a finished machine, though. The steering has no self-centering mechanism, and the build can tip over while running. In one demonstration run it rolls across a floor, then tumbles down a staircase and breaks into separate modules. Those loose ends are what I would most want to see solved next.
Project by JK Brickworks. Watch it on their YouTube channel: