6-Cube Organizer Bookshelf

Mark out all your joint locations on the cut pieces. Predrill and countersink for 2" screws and glue throughout, or use a pocket-hole jig with 1-1/4" pocket hole screws instead.

Attach the bottom shelf's divider pieces to the bottom shelf with 2" screws. Attach the bottom shelf to the sides, applying glue at every point where a vertical cubby divider will line up — a 1x2 leg will reinforce this joint in a later step, but the glue here is what carries the shelf load long-term.

Attach the legs to the sides, flush on all sides, with 1-1/4" brad nails and wood glue.

Measure and cut the horizontal trim pieces to fit the front of the bookshelf, then repeat for the back. This trim ties the whole box together and is what keeps it from racking.

Attach the back trim with 3/4" brad nails and glue. Sand, fill nail holes, and finish.