You'll find full measured drawings and a list of everything I used for this project at http://www.iliketomakestuff.com/how-to-make-king-size-bed/

Step 1: Make the Ground Frames

Cut down eight short 2×4 and two long 2×4. Mark where you’ll add pocket holes.

Use a pocket hole jig to add holes for connecting the frame.

Just screw them together. Then make a duplicate frame for the other side.

Step 2: Cut and Assemble the Cabinet Boxes

Cut down plywood for the top, bottom and back panels for each cabinet.
Cut down drawer dividers the same height as the back panel, and the same depth as the top and bottom panels.

Screw in drawer slides to the dividers. Add one to each side of the interior panels, and to only one side to the outside panels. Draw lines on the back panel to space out your dividers to keep them even and square. Attach the dividers with glue and nails.

Draw lines on the top panel to match the measurements used for the back panel. These will show you where to shoot nails down into the dividers. Make sure the dividers line up with your markings, then glue and nail in place. Flip the cabinet over, and follow the same process for the bottom. Then make a duplicate cabinet for the other side.

Step 3: Make the Drawers

Cut nicer looking plywood down to size for the drawers. Add a 3/16″ channel to each piece using a dado blade, router bit or multiple passes with a normal blade.
Cut down a piece of 1/8″ plywood to size for the drawer bottom.

Glue and nail three sides, then slide in the bottom panel.

Glue and nail in the final side panel.

Add the drawer slide to the sides of the drawers. Repeat for the rest of the drawers.

Step 4: Make the Drawer Faces

I laid my barn wood in position, flush with the back side of the bed.

Then I made a mark right in the center of the drawer divider and drew a line across the whole face.

Using a straight edge, I cut the barn wood along the cut line.

Clamp the piece, on top AND bottom, to the drawer front.

Counter sink and screw the barn wood and drawer front together.

Repeat for all drawers. Keep the pieces in order for continuous grain pattern.

Step 5: Assemble the Pieces

Screw the under frame to the bottom of the cabinet, offsetting it by 1″ from the front and outside edges. This lip makes it easier to open the drawers from beneath.

Add 2×4 braces to connect the two cabinets using two pocket holes on each end of each 2×4. Cut a scrap 2×4 to put under the piece you’re screwing in to keep it at the correct height.

Add pocket holes to the “foot” end of the bed, and align the front face of barn wood. Clamp it in place.

Attach the front face with pocket hole screws.

Cover the 2×4 under frame with strips of pallet slats, trimmed down to 1 1/4″ .