**ZC490 Steps.** N04 Assembly: cut all boards to length, drill 3/32 in pilot holes, glue and screw shelves between the sides, clamp 30 min. -- N08 Load testing: load 25 lb per shelf for 24 h, mid-span deflection must stay under 1/8 in. -- N10 Sanding and finish: sand 120 then 220 grit, remove dust, apply 2 coats water-based polyurethane, 4 h drying between coats. -- N11 Beginner mistakes: always drill pilot holes to avoid splitting, never over-tighten screws, verify squareness before the glue sets. See also [[ZC490 Materials]], [[ZC490 Safety]], [[ZC490 Tools]].