Here is a front view after mounting the sides. The tweeters were a little tight in some places. We used weather stripping around them to seal them up. We used hot melt to mount these carpet pieces. The top 4 tweeters run all the time, the bottom 4 will be switched in for PA use, or for bigger venues.

We used three layers of water based wood filler to close the gaps at the back where the poplar meets the side brace. Edges were rounded off with a power sander. Normally I would rout these, but I didn't want to remove the screws. A flush trim bit in the router took care of protruding edges on the sides.

We need a place to mount the speaker jacks. I found a triangular scrap from the internal braces. With a little sanding, we got it to fill in the butt crack. I used the brad nailer along the top and band clamps to to get the panel attached to the main box. The left and right edges are just glued in place. Plenty strong, and a convenient handle. The third wire will switch on the lower 4 tweeters.