Industrial Bookshelf

Set your Kreg jig to the 1-1/2" setting and drill a single pocket hole on each end of the short 2x2 bottom supports. Before attaching legs, drill a pocket hole for the top on each leg, and rotate the legs so the pocket holes sit on the back of the bookcase where they won't show.

Attach the top with screws driven down from above (at least two small self-tapping screws per joint) or with pocket holes on the back side. Deciding this before assembly keeps the fasteners where you want them.

Set the Kreg jig to the 3/4" setting. On each end of the shelves, drill a pocket hole 3/4" in from the outside edge so it lands in the leg. Attach to the 2x2 legs with 1-1/4" pocket screws and glue.

Check the project is square by measuring the diagonals of the outside corners and pushing until they match. Then attach the 1/4" plywood back with 3/4" brad nails (or staples) and glue, nailing across every joint — the back is what locks the frame square and stops it racking. Sand and finish.