Measure your room’s corner and establish the length of shelving you’ll need.
Use a circular saw to rip-cut sheets of birch plywood lengthwise into manageable 13-1/2” wide boards (Image 1).
Use a table saw to cut the boards to a uniform 11" width (Image 2) (save the cutoff strips for edging).
Set the blade on the table saw to 45 degrees and cut the front edge of the shelves at an angle to create the mitered edge. Because table saw teeth rotate downward, place the wood with the best side up for a smooth cut.
Position the saw fence 2” from the blade. Using the plywood cut-off strips from the shelf boards, place the 45-degree side of each strip against the fence and rip 2” wide mitered pieces for the front edge of each shelf board (Image 3).
Rip extra pieces that can be used for the short angled edges at the ends of the shelves.
Use a tape measure and carpenter’s square to mark the length of the shelf boards.
For the outer ends of the shelves, cut across one end of each board at a 45-degree angle, with the angle of the saw’s blade also set to 45 degrees for the mitered edge strip (this is called a compound cut).
Cutoffs on long boards are easier to do with a circular saw than with a table saw. To make a smooth, exact cut with a hand-held power saw, clamp a straightedge to the board to act as a guide (Image 1). First measure from the saw blade to the edge of the saw’s shoe, then transfer this measurement to the board. Position the straightedge so that the saw shoe is against it and the blade lines up with the cut mark.
With the saw shoe snug against the fence, make a cut across the shelf end (Image 2). Repeat this process on each shelf board.
You’ll need a minimum of two 1x6 vertical supports for each shelf, depending on the length of your shelves – supports should be positioned no more than 30” apart to prevent the shelves from sagging. Use solid wood for the supports, which will be cut to 23” in length. The vertical supports extend from the top side of the bottom shelf, through the center shelf, to the underside of the top shelf.
The finished dimension of the supports is 3/4” thick by 5-1/2” wide. Mark the location of the supports on each shelf. Because the supports are perpendicular to the length of the shelves, determine the center point across the width of each board and measure 2-3/4” in each direction from this point. This will be the centerline of your router cut for each support.
Build a simple rectangular jig to make the routed grooves consistent. Your router base should fit inside the jig and be able to move forward and back only, without wandering from side to side (Image 1). The jig is placed over your support centerlines and each is routed in turn.
Use a 3/4" straight-cutting bit in a plunge router (Image 2) to cut a 1/4" deep groove in the bottom shelf and a matching 1/4" deep groove on the underside of the top shelf. Rout a slot completely through the center shelf.
Before fastening the shelf edges, dry fit each one and use a sander or block plane, if necessary, to make any adjustments needed. Check the fit of the side pieces as well by placing them into position with the long edge strips in place.
When ready, apply a bead of wood glue along the mitered edge of the first shelf lip piece and set it in place against the mitered edge of the shelf.
Use a pneumatic nail gun to attach the lip to the shelf, shooting down through the shelf top into the lip edge. Place nails every 6 to 8 inches. Shoot additional nails through the front of the lip into the shelf, alternating with the top-down nails. Angle the nails for better holding power, but be careful not to shoot through the narrow lip surface.
Complete each shelf by attaching the side pieces with glue and nails.
Add a solid wood 1x2 strip along the back edge of each shelf, using glue and nails. Keep the top of this strip even with the top surface of each shelf. This cleat will be used to fasten the shelf to the wall studs.
Use a 3/4" round-over bit in your router to trim all four edges of the 1x6 supports.
After routing, cut the supports to 23” lengths.
Test fit the supports in the routed grooves and sand as needed to ensure a close fit.
Go over all flat surfaces of shelves and supports with a random orbital sander for a smooth finish.
Sand the shelf surfaces and edges lightly to eliminate blemishes and marks, but be careful not to sand through the plywood’s surface veneer. Be especially cautious on the mitered corners to keep the edges sharp.
Apply a water-based wood stain with a clean, lint-free cloth. Wipe the stain on in the direction of the grain and rub it in well. Stain the tops, bottoms, and all sides and edges of the shelves.
To get into tight corners, wrap a rag around the point of a screwdriver and use the tip to apply the stain.
Allow the stain to dry according to the product directions, then apply a second coat.
Fill all nail holes with wood putty that matches the stain.
Apply three coats of clear, non-yellowing polyurethane, allowing each coat to dry thoroughly and sanding lightly between coats.
Use a stud finder to locate the wall studs and mark their position with painter’s tape.
Measure the intended height of the bottom shelf, and use a level to transfer that mark across the wall.
Have helpers hold the shelf against the wall on your level line (Image 1), then transfer the stud locations to the cleat along the bottom rear edge of the shelf.
Use a countersink drill bit to bore pilot holes for mounting screws on each of the stud marks. Pre-drill all of the shelves at the same time (Image 2).
Use a power drill/driver and 3" drywall screws to mount each shelf to the wall. Be sure the screws are driven securely into each stud. Provide temporary support with a telescoping pole or other brace until the permanent supports can be installed.
From underneath the bottom shelf, bore 3 evenly spaced 1/4” holes into each of the routed support grooves.
Insert the upright shelf supports into the routed grooves and secure with 1” wood or drywall screws from below.
Measure up 11” from the bottom shelf and drill holes in the upright supports for metal shelf pegs. Place two pegs on each side of the supports to support the middle shelf (Image 3).
Line up the slots routed in the middle shelf with the vertical supports, then lower the shelf down on the supports until it rests on the pegs.
Place the top shelf onto the vertical supports, making sure all the shelf parts are aligned correctly. From above the top shelf, drill 1/4" holes down into the vertical supports, and insert 1” screws to secure the shelf.