Stand two pieces of 12-by-24-inch, 1-inch medium-density fiberboard, or MDF, on a 24-inch edge, parallel with 12-inches between them.
Insert three pieces of 12-by-12-inch MDF between the parallel 24-inch pieces, with one piece centered, and the other two forming corners with the ends of the 24-inch panels.
Glue the 12-by-12-inch pieces in place, checking that the corners are right-angled with a carpenter’s square. The 24-inch panels are the bench top and base, with the 12-inch panels the bench sides and cubby divider.
Drill five evenly spaced pilot holes that are countersunk and sized to fit 2-inch screws through the top and base into the ends of the side and divider panels, then secure with 2-inch screws.
Position a piece of 14-by-24-inch 1/2-inch-thick MDF over one of the open sides of the bench for the back. It should be flush with the top and bottom of the bench top and base, as well as bench sides.
Secure the back in place with 2-inch screws driven every 5 to 6 inches around the perimeter of the back of the bench and into the divider panel as well.
Position two pieces of 12 1/2-by-17-inch 1-inch MDF over the sides of the bench. The bottom of these panels should be flush with the base, and the tops extend over the bench top by 3 inches to create a small side to the bench top. The back edge of these side panels should also cover the end of the back panel.
Secure the side panels in place with 2-inch screws driven every 3 to 4 inches around the perimeter of the inside of the 12-by-12-inch side panels into the 12 1/2-by-17-inch panels.
Fill the tops of all the visible screw holes with wood putty and scrap flat with a putty scraper. Let dry before painting the bench as desired. Once the paint is dry, insert a storage basket in the two cubbies of the storage bench.