Slicer: PETG or PLA, 0.2 mm, 3 walls, 15% gyroid. Fit clearance 0.18 mm — dry-fit before gluing.
3MF: 9 named objects, oriented and placed on the plate — import, assign filaments, slice.
No supports anywhere. Every part is a flat plate printed on its face, so nothing overhangs. Don't auto-orient or split to objects.
Assembly: press each panel onto the deck's tenons (0.08 mm). Drop a staple into the notches at each end — its legs run down outside the panels and stop them splaying. Set the deck ends over the ramps' lugs, then lower the whole bridge onto the abutments, whose keys rise into the end posts. Everything drops into place and nothing slides.