How to Build an Enclosed Floating Shelf

Decide the floating shelf's length and width based on the size of the room and what items you plan to place on the shelf. Measure out the shelf's length and width on a piece of 1/2-inch plywood twice, to create two rectangles. Cut the rectangles out of the plywood with a table saw. These two pieces will be the top and bottom of the floating shelf.

Mark the floating shelf's length measurement onto a 1-by-2-inch poplar strip, twice. Cut the poplar along the marks with a miter saw, to create two long strips. These strips will form the floating shelf's front and back edges. Transfer the floating shelf's width measurement twice to a 1-by-2-inch poplar strip and cut on the marks to form two short strips, one for each of the floating shelf's side edges.

Lay the strips you just cut on a work table. Place one of the long strips between the two short strips. Butt the strips up at each end to form two 90-degree corners. Place the second long strip between the two short strips, on the other end, to form a rectangle. Move the second strip toward the first strip about 1 1/2 inches, so the short strips now extend slightly past the long strip. Glue and nail the strips' ends together using wood glue and nails.

Measure the space between the two long poplar strips. Mark this measurement twice to a new 1-by-2-inch poplar strip and cut along the marks to form two new short strips. Evenly space these strips within the floating shelf's framework that you built in Step 3, with their ends touching the two long strips. Glue and nail these two strips' ends in place.

Apply glue along the top edges of each poplar strip in the floating shelf's framework. Lay a piece of 1/2-inch plywood you cut in Step 1 over the framework. Staple the plywood to the framework. Flip the shelf over and repeat this step on the other side.

Mark the floating shelf's length and width measurements onto 1-by-2-inch facing strips. You will need one length strip and two width strips. Cut along the marks using a miter saw, set at a 45-degree angle. Miter both ends of the length strip at a 45-degree angle and miter one of each of the width strips' ends to a 45-degree angle. Cut the width strips' other ends with a straight cut. These strips will be placed around the floating shelf's three visible edges to hide the plywood's edges.

Apply glue to the floating shelf's sides and front edge. Place the strips you cut in Step 6 over the glue. Position the width strips so the mitered ends come together with the long strip's mitered ends to form 90-degree corners. Secure all three strips in place with finishing nails from a pneumatic nail gun, or a hammer.

Scoop a small amount of wood spackle out of its container with a 1 1/2-inch putty knife. Smear the spackle over each staple and nail hole in the top plywood board, the front facing strip and the two side facing strips. Sand the entire shelf with 220-grit sandpaper. Paint or stain the floating shelf to the color of your choosing.