An interactive 3D build of IKEA's BILLY bookcase, step by step
IKEA – 3D Guide
A web tool rebuilds IKEA's BILLY bookcase in 3D, following the official manual page for page: the same parts, the same 82 pieces of hardware, in the same order. Step through with arrows or a timeline, open the manual beside the build, or switch to the LACK table. It also explains how a cam lock actually clamps two panels together.
The dowels only line things up; the cams do the clamping.