Measure the width, height and depth of the area to be filled with the entertainment center. Note these measurements carefully to ensure the dimensions of the center are to your liking upon installation. Take into account the size of your TV, the number of components you have (or will have) and if you will require extra shelving for books or storage.
Draw an outline of how you want the center to look, using your measurements as a general guide. You may also find design examples at your local home improvement store if you're unable to draw an adequate design. At this point, you're trying to get a mental picture of what will fit best within the space allocated for the center.
Purchase a cabinet kit that matches the design elements and dimensions you desire and require.
Clamp the cabinet sections together and drive screws through the front and rear structural pieces of the cabinets using the drill and screw bit. Take care to ensure any screws do not protrude into the cabinet space where they may injure someone or damage equipment.
Once the pieces are secured together, install a wood filler strip (provided with the cabinets) over the visible seams on the face of the cabinetry.
Cut holes in the back or sides of the cabinets with a jig saw to allow wiring to be run through the back or sides of the entertainment center.
Measure the top of the joined cabinet pieces to determine the size of plywood (or desired material) necessary to create the cabinet top. If your entertainment center is free standing, you may include extra length on the front and sides of the cabinet top to facilitate an over-hang for aesthetic purposes.
Mark the dimensions of the counter top on the top side of the counter top material and complete necessary cuts using the circular saw until the counter top is reduced to the desired size. Then place it on top of the cabinet body and nail into place using a nail gun.
Cut additional pieces of material on a set of saw horses, with a circular saw, to create shelves or other design elements. If you're building the entertainment set into an alcove, you can nail these sections (which comprise vertical supports, shelves, and lateral support pieces) to the wall and to each other.
If you're building a free-standing entertainment center, it will be best to purchase a cabinet set that has upper cabinet elements, since a proper anchoring point will not likely be available.
Place the plastic shelving hole template onto any vertical support pieces and drill the holes, following the template, with a drill and drill bit. If you've purchased a cabinet set with pre-built upper elements, skip this step.
Use a router to soften the edges of the counter top, making them safe and rounded, while adding design appeal. There are many different router design bits to choose from, so you may test your different bits on a piece of scrap wood to determine the best design.
Assemble any remaining upper structural elements by gluing and then nailing the pieces together. Use your level to ensure that the cabinet structure is level; this includes wall-mounted and free-standing entertainment centers. If the structure is not level, use wood shims on the support legs to prop up the low sections of the entertainment center until the structure is level.
Nail finished pieces over the front of any open shelves or structural cabinet elements not meant to be seen after the project has been completed. For example, the front edge of a shelf or the particle board substructure of the cabinets is to be covered with pieces of wood that are aesthetically pleasing and provide a "finished" look.