Introduction: Scrap Wood Cell Phone Amplifier

About: Enjoy being creative and figuring out how to solve a problem!

My cell phone has very poor sound, especially once I put this case on it. So I decided to make a sound amplifier for it out of only materials I had around my shop. This is a very simple build that anyone can do. All power tools can be substituted for hand tools and if you really wanted to, you could change the scrap wood for some very nice exotics. Good luck and I hope you enjoy the build.

Step 1: Materials


-For this build I literally just used scrap pieces I had around my shop. The only guideline I had for it was to make sure the front & back plywood was around 12" long and around 4" tall. Also, that the spacer board was as thick as my phone. This will change depending upon the size phone you have!

-Wood Glue

-Nails (I used 1-1/4" pin nails)


-Spray Lacquer


I used a lot of power tools for this build, but every part could be done with hand tools. It would just take a bit longer.

-Miter Saw

-Nail Gun

-Drill Press




Step 2: Cutting the Pieces

So since this whole project was done from scrap I worked with what I had. First I cut my ply in half. This made each piece around 12" long and 4 " high. For the spacer pieces I didn't measure at all, I just held my back pieces up to the spacer and made sure each piece was the exact length of where it would be attached. You do want to make sure to use your phone as a spacer this way you know that your phone will fit comfortably into the space it's needed. The last thing you want to take into account, which i did not do at first, is where the speaker is on your phone. My speaker is on the bottom right corner, as seen in the picture I did not take this into consideration. I cam back later and cut the piece smaller to allow the sound to move from the phone to the open spaces.

Step 3: Assembling the Back

Now that all the spacer pieces are cut, go ahead and glue and nail them into place. All I did was make sure the spacers and the outside edge of the back board were flush when attaching the spacers. I also used my phone to make sure there was enough space so the phone could move, but not enough that it would fall to the side.

Step 4: Getting Measurements for Phone Area

Now to figure out where the phone would go on the front I just held the front and back pieces together while I laid the whole thing face down.Then I removed the back and this showed me where the phone would be once assembled. I traced the outline of the phone and then gave a small lip on the bottom so the phone won't slide out.

Step 5: Getting Measurements for Sound Holes

For holes that would release the sound I just grabbed some quick measurements of center and then transferred them to the front piece.

Step 6: Cut All Openings

Now it was time to actually cut all my markings out. I started with the holes, I used a 1" Forstner bit on my drill press to cut them out. In hindsight I would make the hole bigger, but you leave and learn. Next, I moved onto the phone cutout. I used my jigsaw to cut a nice rectangle space ensuring to leave the small lip at the bottom.

Step 7: Glue Up

Now that all pieces are cut go ahead and glue the front piece on. I opted not to use nails on this portion so it would give the front a clean look without nail holes. so just apply a small bead of glue and clamp it together.

Step 8: Profiling the Edges

This step is completely optional. After I assembled the amplifier box I thought it would look better if the edges had a slight round over. So I took my router and gave the sides a slight profile.

Step 9: Quick Test

Now that everything was together I decided to give the box a quick test run. It fit the phone perfectly, just enough lip at the bottom to keep the phone snug, while still showing the whole screen.

Step 10: Sand

Since I was happy with the finish I move on to sanding and cleaning up the box. Just make sure to give a light sand to all the edges as well!

Step 11: Finish

Now the box could be left in the bare wood color, but I decided I wanted a nice stain on mine so I put some finish on it. After, the finish dried I gave it a couple spray coats of a gloss spray lacquer.

Step 12: Enjoy

Now that everything was dry and finished I threw in my phone and enjoyed the great look and sound of my scrap wood amplifier!

Audio Contest 2018

Participated in the
Audio Contest 2018