This is the BILLY bookcase, 80 × 28 × 202 cm, built from IKEA's own assembly manual (AA-1823127-9). The manual on the left is the real one, page for page. The 3D build follows it step by step: the same parts, the same hardware counts, in the same order, seen from roughly the angle each drawing uses.
Two sides, a top, a bottom, a fixed middle shelf, a plinth, four loose shelves and a back panel folded in three. And 82 pieces of hardware: 16 wooden dowels, 12 cam screws, 12 cam locks, 18 nails, 16 shelf pins, 2 wall brackets with 2 screws and 4 washers. The Hardware in count follows each one as it goes in. The cyan outline against the wall is where all of it ends up.
BILLY holds together with cam locks. A cam screw goes into the side panel and stands proud of it. When the board goes on, the screw's head drops into a round cup (the cam) set into the board's face. Turning the cam half a turn clockwise drags the head along a spiral ramp inside it and pulls the two panels tight. The dowels only line things up; the cams do the clamping. The back panel, nailed on, is what stops the case racking out of square.
