Plan and Sketch the Workbench Dimensions and Assemble Tools and Materials
Design and draw the workbench to confirm dimensions and then assemble tools and materials. You will be using power tools and cutting lumber, so be sure to wear safety glasses and a dust mask.

Set Up a Temporary Workbench with Sawhorses and Lumber
Set up a temporary workbench with sawhorses and some of the lumber for the project.

Make a List of Wooden Pieces and Dimensions to Cut
Make a cut list of the dimensions and numbers of wooden pieces that you will need to cut. Each dimension will require that you saw multiple pieces, so save yourself time by cutting identical pieces in batches.

Position a Two-by-Four as a Guide for Multiple Straight Cuts
Position a two-by-four horizontal to the ground and at right angles to the compound miter saw blade as a guide.

Measure from the Saw Blade to the Required Cut Length
Measure from the saw blade and mark the required length for the legs on the leveled guide for cutting multiple pieces to the same dimension. Make sure the guide is stable in this position.

Extend the Mark with a Combination Level and Ensure Everything Is Level and "Square"
Use a combination square to extend the mark down the side of the two-by-four and ensure that the line is perpendicular to the wood. The "square" positions of the lumber and the line, relative to each other and the saw blade, are critical in cutting legs that will stand properly on the floor to support the bench without wobbling.

Clamp a Stop Block at the Mark and Butt Each Piece Against It As You Cut
Clamp a stop block against the line. The two-by-four and stop block serve as a template to ensure all the leg components you cut will be of identical size. For each leg, you will cut a pair of two-by-four lengths. In a later step, you will sandwich them together to make a single sturdy four-by-four leg. Cut all the components for the legs, then re-adjust the stop block as necessary to cut the other ?multiple? components on your cut list to measure.

Notch Each Pair of Two-by-fours for the Legs to Accommodate a Rail/Brace
Notch the pairs of leg two-by-fours at the appropriate distance from their ends to accept a bottom rail/brace at right angles and form a mortise joint. You will cut the braces from two-by-four as well, so each notch must accommodate half the thickness of a two-by-four. Cut the notches by making repeated passes across the wide face of the two-by-fours with a sliding compound miter saw, but ensure that you cut only halfway through the board.

Apply Glue to Two Pairs of Leg Components and a Rail
Set out two sets of leg components and a bottom rail/brace. Apply wood glue to the interior surface of each pair of two-by-fours and their notches.

Align Two Sets of Leg Components to Accept a Horizontal Rail/Brace
Position two of the leg components with the notch upwards, aligned exactly so the brace will lie in the notches with its ends flush with each two-by-four. Lay the brace across them and seat it in the notches.

Set the Rail in the Notches and Fit the Second Half of Each Leg Over the Rail
Set the other two-by-four in each pair on top, fitting the notch on the brace. You now have two four-by-four legs connected by a two-by-four brace.

Screw the Leg Halves Together Through the Notch and Rail
Screw the leg halves together through the mortise/rail for a more secure joint and in several other places along the leg. When held in the correct orientation, the leg assembly now resembles a capital letter "H" with the cross bar formed by the rail well below center.

Glue and Screw a Second Rail Across the Top of the Legs
Glue and screw a second rail across the top of the legs. This completes construction of a single end-frame for the project. Construct the other end-frames in the same way.

Connect Two "H" End Frames Together with Side Rails
Connect two end-frames together with side rails. Clamp them into position and secure them with screws driven through the side rails into the end frames. Position the screws so you drive them through the component two-by-fours of the legs rather than in the glued crevice between them. Use the same process to connect the other side rail.

Set Two-by-fours Across the Lower Cross Rails to Form a Shelf
Set two-by-fours the same length as the side rails in place across the lower cross rails and screw them in place at each end. Laid side-by-side, these will form a storage shelf.

Measure and Mark Top Panels for the Workbench on Sheets of 3/4-Inch MDF
Measure and mark panels for the top of the workbench on sheets of 3/4-inch MDF (Medium Density Fiberboard) laid out on your temporary work surface.

Use a Clamp-on Straightedge as a Guide for Cuts Made with Your Circular Saw
Use a clamp-on straightedge as a guide as you cut the MDF to measure with a circular saw. It helps guarantee and perfectly straight cut.

Position the MDF Panels Flush with the Supports on the Back Edge of Each Workbench Section
Set the MDF panel on top of the workbench support, making it flush with the supports at the back with a slight overhang at the front.

Pre-drill the MDF Panels to Countersink the Screw Heads
Pre-drill the MDF workbench top with a countersunk bit. The screw heads must be at or slightly below the surface so they do not scratch materials or otherwise catch on whatever you build on the workbench.

Complete the Section by Securing the Top Panel with Screws
Attach the top with screws. This step completes one workbench section/module. Build the other two workbench sections to an identical size using the same process.

Set the Three Completed Workbench Sections in Place, Leaving the Correct Space for the Fourth
Set these three workbench sections in place, leaving the opening for the fourth section--it will be lower than the others to accommodate the compound miter saw.

Clamp a Two-by-four Across the Front of the Gap Between the Workbench Sections
Clamp a two-by-four across the front and back of the gap between two of the full-height workbench sections. This cross member will position and brace the two adjacent workbenches and provide a support for the dropped surface of the fourth/final bench.

Drive Screws through the Cross member into the Constructed Four-by-four Legs
Secure the cross member immediately beneath the side rails, driving screws through it into the constructed four-by-four legs.

Attach an identical Cross Member at the Back of the Gap
Attach an identical cross member at the back of the gap, using the same process.

Cut and Secure an MDF Panel for the Top of the Fourth Workbench Section
Cut and secure an MDF workbench top to the fourth section, sliding it into the dropped position on the cross members.

Cut a 1/4-Inch Hardboard/Masonite Panel for Each Workbench Section and Apply Double-faced tape
Cut an additional top panel from 1/4-inch hardboard/masonite for each of the four workbench sections. Workbench tops often take a beating over time and require periodic replacement or refinishing. Adding the removable Masonite panels will facilitate replacement when the time arrives. Turn the Masonite panels upside down and stretch double-faced tape along the edges.

Peel Off the Backing and Stick the Panel to the Permanent MDF Surfaces
Peel off the backing strip, flip the Masonite over and stick each panel to the MDF surface on the respective workbench sections. Press it firmly in place, after positioning it flush with the edges of the MDF panels. Repeat for the other three sections.

Place the Sliding Compound Miter Saw in Position on the Lower Section Where the Workbench Tops on Ei
Place the compound miter saw in its place on the fourth/lower section of the workbench--its top was set lower so that the bench tops to the left and right sit at the identical elevation as the saw bed and will support longer pieces of lumber as you cut them.