- Plywood: an 8 mm disc, Ø340 mm, on the box side of the arcs. The chain leaves only 10 mm to the carrier plates, so 8 mm keeps 2.4 mm clear. The lip on the back of each arc hugs the disc's edge, so the arcs come out round by themselves. Drill through the arcs' holes for 3.5 × 12 countersunk screws, 3 per arc.
- Print: flat, countersinks down, no supports. PETG, 5 walls, 40 % infill.
- Chain: 290 links per side, a carrier every 58 links. Pitch Ø 363.9 mm.
- Print one arc first and lay a piece of chain on it.