Interlocking Shelves (Building Cases)

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If you are always looking for bookends to keep long rows of books divided into sections, consider this case. These storage boxes utilize the time-tested concept of interlocking boards as the basis for a system of storage boxes that can be scaled to suit almost any storage need.

The project shown is built from plywood and is based on a 12-inch cubic module. If you plan to store record albums or a collection of dolls, for instance, design your own system of interlocking shelves based on a suitable module.

The number of boxes, as well as the size, is variable. The unit shown has 24 boxes, but using the same principle, you can make a case with as few as 4 or as many as needed for a whole wall of storage. To stabilize the unit, you may have to build a base to put under it. To keep tall units from tipping forward, attach top to wall using a cleat screwed into wall studs, which is then nailed or screwed to the top of the case.

Materials needed

The unit shown is constructed from 12-inch strips of solid-core plywood. Plywood was chosen for its strength as much as for its looks. The whole unit could also be slightly scaled down in order to use 1 by 12 pine shelving. However, because notches are cut halfway through each board in several places, the weaker pine shelving can break once shelves are put into service. To get around this problem, add a plywood back, driving nails into back edges of shelves.

Building techniques

Whether you include a plywood back or not, follow this procedure.

1. Cut 4 outer pieces (top, bottom, and 2 sides) ¼-inch deeper than shelf boards and vertical dividers.

2. Cut a 3 rabbet in each outer board. On the inner back edge of each outer board, cut a rabbet ¼ inch deep and 3/8 inch wide.

3. If more than 1 sheet of plywood is needed for back panel, cut plywood so that joints fall where they will be obscured by a vertical divider.

Building a 24-cube unit

1. From each of 3 sheets of 3 hardwood plywood stock, cut 3 strips 12 inches wide by 96 inches long (9 strips in total).

2. From 12-inch-wide strips, cut 2 outer vertical panels 72 inches long, 3 inner vertical dividers 72 inches long, and 7 horizontal panels 47¼ inches long.

3. Select 4 of these strips for top, bottom, and sides of case, and mark them very accurately for rabbets and dadoes. Dimensions shown on illustration are from ends of individual boards to center points of dadoes. This means that rabbets will be inset from ends of boards, and dadoes will be centered on their marks.

4. Using a ¾-inch-wide dado blade or router bit, cut 3 rabbets and dadoes.


Shelf dimensions: Optional back panel

5. Cut notches in remaining horizontal pieces. Lay out notches to correspond exactly to locations of dadoes you previously cut into top and bottom pieces. Make notches ¾ inch wide and just over 6 inches deep. They should extend from back of board to just beyond the midpoint.

6. Cut notches in remaining vertical boards. Position these shorter boards against the outer (longer) boards to mark position of cuts. Note that half of the rabbet on each end of each outer board should extend beyond ends of shorter inner boards. This ensures that notches are in the right places.

Cut these notches ¾ inch wide, from the front of each board to just beyond the midpoint.

7. Check cut pieces by aligning them with their adjacent pieces. Notches and dadoes should line up. If they fail to line up, you will have a difficult time fitting all the pieces together, although a small amount of error can be accommodated.

8. Using a rubber mallet, assemble pieces starting with the grid of inner boards. Add top and bottom pieces to inner grid, securing them in place with glue and finishing nails. Check assembly for square, do not disturb, and allow glue to dry.

9. Fit vertical side panels, securing them with glue and finishing nails. Check again for square, and allow assembly to dry. Apply the finish of your choice.

Grid can be used as is for storage. If you want to make it more of a display piece and dress it up a bit, you can add a base or pediment, as shown in the illustration.


Shelf assembly: Notch from back on horizontals; Recessed base: Cut from leftover plywood or use 1-by lumber; Side view: 2-by bases with milled top edges 2x2 cleat across top; Screw into studs; Base options: 2-by bases with milled top edges, Mitered corners.

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Full guide: How to Plan & Build Bookcases, Cabinets & Shelves

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Modified: Monday, 2010-12-06 16:41 PST