Begin with the Plywood
To begin this project, use your table saw to rip the plywood stiles and rails to width and length (pieces 1 through 4). I am sure that any good quality saw blade will work for you, but I use a Freud 80-tooth crosscut blade for all of this work (even the ripping steps). I find that it provides a silky-smooth edge, and that means less sanding for me! Now grab a 1/4″-thick piece of hardwood (I used walnut in this case) and rip enough stock to create the stile and rail edging (pieces 5 and 6). Next, glue and clamp the edging to the front rails and stiles — you’ll find that they’re the same length. While you are waiting for the glue to dry, go ahead and move back to the table saw to rip sufficient material to make the perimeter trim (pieces 7 and 8). The following construction process is stone simple, but I recommend that you take a bit of time to look at the Drawings and to check out the photos — it’s very important that you follow the right sequence.
Once the glue has completely cured on the front stiles and rails, take them out of the clamps, scrape away any excess glue, and sand them smooth. I prefer a 3″ x 21″ belt sander for this task because it levels the hardwood edging perfectly even with the plywood face.
Now it is time to put the plywood frame pieces together. The plywood pieces fit together with the hardwood edging lining the opening in the frame. The back stiles and rails simply butt together as do the front stiles and rails. But the front stiles and rails overlap the butt joints in the lower layer, essentially making a built-up lap joint. I used screws and glue to secure the plywood pieces one to another. Lay out and pre-drill the through holes in the front stiles and rails, adding a countersink to each location. I used 1/2″ x #6 screws and I prefer Titebond® glue. To help me glue and then precisely place the stile and rail pieces together, I used short pin nails fired from a 23-gauge nail gun to tack the pieces together. Then you can drive the screws home, being certain that the heads are seated just a hair below the surface of the front stiles and rails.
Even though I took exceptional care to line everything up accurately, the outside edges did not align perfectly. So, after the glue had cured, I stepped over to my table saw and trimmed the long edges just a tiny bit. The only thing left to do to the plywood frame subassembly is to glue a 1/4″-thick border of hardwood all around the perimeter, using the trim that you cut earlier. Glue and clamp the trim in place and allow the glue to cure. Wrap up by using your belt sander one more time and sand the face flat.
I’m betting you’ll notice early on that one of the nicer features of this construction plan is that, because the front and back stiles and rails are different widths, when they are put together, this size difference creates a perfect rabbet just behind the front stiles and rails. It is into this rabbet that your picture will eventually be placed.