I made the frames out of three 16-foot lengths of primed 5/4x4 stock, cutting all of the pieces for both tables to length at the same time. Before assembling the frames, I clamped the four long stiles (two for each table) and eight shorter rails (two end rails and two intermediate rails per table) together and laid out the locations for approximately 1 1/2-inch-wide slots in the edges of the stiles and rails.
I used a router with a straight bit to make the slots 1/2 inch deep, first scoring the layout lines with a utility knife to prevent blowing out the edges of the 5/4 stock. After the frame is assembled, the slots will allow me to make cuts either along or across the frame without making saw kerfs in it by simply aligning my cut line with the slots. Of course, eventually the edges of the frame will be riddled with saw kerfs, but as long as they aren’t too deep, they won’t affect the frame’s integrity.
You could fasten the frame together with toe screws, but I prefer to use exterior-grade pocket screws because I think they make a stronger connection. Probably a pair of screws at each joint is adequate, but I added a third one for a little extra strength. I didn’t bother using glue, but you could.
I used a Kreg portable pocket-hole jig to make the holes, for both the stile-to-rail connections and the connections between the frame and the MDO top skin.
I assembled the frame with 1 1/2-inch-long, exterior-grade, coarse-thread Kreg screws.
Each frame is reinforced with a pair of intermediate rails pocket-screwed to the stiles.
After I placed the frame on top of the MDO skin so that the edges were aligned, I used shorter, 3/4-inch-long pan-head screws to fasten the frame and top skin together. The shorter screws are needed to avoid penetrating through the 1/2-inch-thick sheet stock, and require a Kreg Micro-Pocket drill guide for drilling the pocket holes.
Once the table was assembled, I flipped it over and marked layout lines on the top skin with a Sharpie permanent marker every 6 inches on-center. On the 1-foot intervals, I extended the lines the full height of my layout square; in between, I drew the lines only 6 inches long.
I also extended the lines onto the sides and ends of the table, making it possible to read them even when the table is covered.
For about $200 in materials and a couple of hours of labor, I built two tables that will stand up for years to daily use and abuse on the jobsite—a pretty good investment.
The layout lines are a handy reference when cutting stock to length.
When the table is flipped over, sawdust doesn't collect on the work surface, but doesn't fall to the ground either. That makes cleanup easier at the end of the day.