Microwave ovens, as one of the larger appliances in a kitchen, can take up valuable counter space. Make a dedicated shelf for a microwave to give yourself more room and to give it a custom, built-in look. By building your own shelf, you can customise the height of it to be most convenient for the cook, too.
Measure the space where the shelf will go to determine the dimensions of the 3/4-inch thick board needed. If your microwave shelf will be underneath and flush with a cabinet, measure from the back wall to the outer door of the cabinet. If the shelf is freestanding, the depth of the shelf need only be as deep as the microwave itself, but a board that is at least 12 inches wide is recommended to provide adequate support. Measure the length of your microwave to determine minimum length for the board. Consider whether or not you intend to leave space on the shelf for other appliances, decorative items or dishware, and purchase a longer board if so.
Purchase a board cut to the dimensions decided upon in Step 1. Sand all edges. Check the top of the board for splinters, gouges or knotholes. Fill any imperfections with wood putty, smooth the putty with a putty knife to create a level surface and let it dry for at least an hour or for the time recommended by the putty's manufacturer. Sand the puttied areas smooth to be level with the board's surface.
Paint or stain the shelf, preferably in a colour to match the existing cabinetry or wall colour. Brush on several thin coats of paint or stain, allowing each to dry completely before adding another, rather than trying to cover the board in one thick coat.
Draw a guide line with a pencil on the wall or side of the cabinet where the shelf will be installed. Use a carpenter's square for shelves that will abut a cabinet on one or more sides; rest one side of the square against the cabinet, flush with the back wall, and draw a line along both edges. If the shelf is freestanding, measure the distance from the top of the kitchen counter or floor to where you want one end of the shelf to rest. Make a second mark at the same height where the other end will rest, then draw a horizontal line between them. Place a level over the line to ensure it is straight. Make adjustments as necessary.
Mark where the screws will be placed. Hold a shelf bracket up to the wall on one end of the guide line drawn in Step 4. Place the pencil through each hole in the bracket that touches the wall, and create guide dots on the wall. Repeat on the other end of the guide line. Drill 1/4-inch pilot holes in the wall over the marks.
Line up the brackets over the pilot holes and use a hammer or mallet to tap the molly bolts into place through the brackets. Use a slotted screwdriver to turn the screws in the molly bolts so they are firmly attached to the wall.
Set the shelf on top of the brackets. Place the pencil through the holes in the brackets and mark guide dots on the underside of the shelf to indicate where screws should go. Drill 1/8-inch deep pilot holes on the bottom of the shelf over the marks. Set the shelf back on the brackets and fasten it in place with wood screws.