How it's made. A 240 mm ring in PLA, printed upright with no supports: a 56 mm track with a 2.4 mm floor, a 42 mm outer wall and a 28 mm inner one, each leaning in over the track at 45° with rounded edges, so the gap between them is 32 mm — and the ball is 36. The ball is printed in place inside the track, standing on a 3 mm tab a hair above the floor; snap the tab and it rolls, and it can never leave. The name is cut 0.8 mm into the outer wall, or stands 0.8 mm proud in its own colour. Wipes clean; no small parts.