I made this over the course of a couple of days, pretty easy, just be sure to measure twice and cut once!

Step 1: Getting Started

Cut 4 pieces of select pine (free of knots) to the same dimension. This will vary by phone size and cases etc. I measured with case as I have no plans to disassemble my case with each use.

Step 2: Making Holes

I used a 3 1/4" hole cutter on 3 of the pieces. After I cut one hole, I clamped to the next piece and drew down the drill press to mark the next piece. I then drilled that piece and did the same procedure with the third one. This help ensure the 3 holes line up when gluing and minimizes sanding of the sides later.

Step 3: Glue the 3 Hole Pieces

I next glued and clamped the 3 pieces with the holes and let set for the night.

Step 4: Routing the Sound Channel

Turning the 3 piece glued assembly face down I traced my phone to a depth I felt would hold it securely without it being too wobbly when inserted into the final project. I clamped the work piece down to my bench and slowly and carefull routed a depth equal to the thickness of my phone with case. I then, with a pencil, manually drew the channel from where my phones speaker was to the sound holes in the work piece. I then carefully routed that channel out. Before moving to the next step, I used a drum sander on my drill press to sand the cut circles smooth.

Step 5: Sanding and Gluing the Back Piece

The next step was to glue the back piece on the work piece. First I sanded the face to make it easier than trying to sand it after the glue up. I clamped and let sit for the night. Be sure to use a wet cloth to wipe out any glue in the speaker that squishes out. Afterwards, I palm sanded all sides smooth. I finished with several coats of spray polyurethane.

Step 6: Finished Speaker

The finished speaker amplifies sound quite well. Its a handsome looking block of wood with great pine graining. Serves the purpose when I use it to just play music for myself without a crowd or party. I have attached a video but it doesn't do justice to the sound amplification.