Once I had the measurements and wood pieces cut to the right size, I used a Kreg Jig to make pocket holes to attach two sides together for each leg piece. Then I glued and nailed the other side in since I didn’t have enough space for pocket holes on the other side (my drill and the pocket hole bit wouldn’t fit. I’m sure there is probably some tool that allows for this but I don’t have it.)
Once I built each leg, I made the center connector piece that is the bridge across the top. I used pocket holes to connect it to each leg but I also reinforced it with an extra piece of MDF nailed in. (Sorry this picture is so sunny)
I put the entire mantel in place and so far, so good! It was a snug fit, which was good. There were a couple of gaps here and there but they would get covered by trim. I also added a top piece which is nailed to the mantel but not nailed to the stud in the wall yet. I can’t attach it to the wall until the quartz it in place, not to mention I wanted to take the entire mantel outside and spray it with paint.