A few months ago at Maker Faire, I met a couple guys who started a company called Trash Amps that makes DIY amplifier kits. These things are really cool: you get a printed circuit board, a tiny speaker, and all the components needed for assembly. The fun part is that you can use or make whatever you like for an enclosure. Their flagship amp is intended for use in a recycled Mason jar.
I bought a kit and spent a lot of time brainstorming ideas for a box to contain it. I thought about all different types of boom boxes. One thought that intrigued me was to make the enclosure look like a retro, 50’s style radio. That got me thinking that another cool idea would be to purchase an old radio at a thrift shop and convert it to an MP3 player. Of course, that wouldn’t make a good woodworking project.
Then Wyatt came up with the fantastic idea of the literal boom box: one of those old timey plungers used to detonate dynamite. I think mostly I’ve only seen them in cartoons, but a quick Google search pulled up all kinds of awesome examples of actual vintage ones! Mine is based on a couple of these as well as the Wile E. Coyote version.
Building the box
I glued and tacked together scrap plywood to form all the sides of the box except for the top and the face.
This board will support the face and provide a place to attach the removable top.
At the hardware store I found some metal pieces to help trim out the box and make it look more authentic. I spray painted these all with a hammered steel dark gray. Then I drilled holes for the bolts to attach the top, a hole for the plunger. and a hole in a dowel to use for the handle.
I cut a bunch of very thin strips to make the “steel” edge braces.
I taped these all together so I could drill holes in all of them at the same time.
With that same metallic gray spray paint these will look like metal.
Assembling the electrical components
The Trash Amps kit has easy instructions for assembly. There are just a few components to solder together. Super easy.
I used very thin plywood for the face of the box and drilled three holes into it. One for the speaker, one for the input jack, and one for the toggle switch.
To protect the speaker I duct taped a small swatch of wire mesh onto the backside of the face.
I spray painted the box red, then lightly sprayed it with black to give it a well-used look.
Next, I attached the speaker, the battery holder and the PCB to the face of the box, then glued and tacked it into place.
These two screws are what the top attaches to. I held them in place with epoxy around their heads.
Then I attached all of the decorative pieces.
To make the plunger I attached the dowel to a threaded steel rod using nuts.
The amplifier will work with any MP3 player or phone, and you can plug a guitar into it.