the other sides were done the same way, but with a gap between the ends. you can see I cut a half lap in the plywood and a piece of walnut. I left the walnut proud and planed it off after gluing. Instead of cutting the walnut connector to the perfect width, I left a small gap. This was to give me flexibility when it came time to square the corners. I glued it when they were square, then ran a shallow cut along the line where the walnut meets the plywood on the outside and inlayed a piece of scrap mystery hardwood the same width as the kerf.