In serious need of some tunes for the poolside and for the bar-b-ques this past summer and not wanting to spend some serious coin on a quality music player, I decided I would build my own MP3 boombox. I took an inventory of what I had on hand(speakers, amp, plywood,etc.) and decided I had ALMOST everything( with the exception of a battery which I figured I could buy) I would need for this project. As luck would have it I was given six (6) SLA 6V, 10AH rechargeable batteries. Taped together and by connecting one positive (+) post to one negative (-) post I ended up with three (3) 12V batteries. As it turns out I also had an old DieHard portable power pack which helps keep the batteries charged. I would like to apologize in advance for a lack of step by step pictures, but I took what few pics I had several months AFTER I had already built this project. I only remembered to take a couple during the build, so again, I apologize. I would like to add that this is my very Instructable so please bear with any mistakes (lack of enough pictures and steps) I have made !

Step 1: Inventory of Items Used.

First and foremost I decided to go with 3/8" plywood which I figured would be strong enough to take on any abuse and still keep weight down to a minimum.
I had an old 12V Jensen 20W X 20W mini amp that seemed like it would be loud enough for the pool or the beach.
For the speakers I had a pair of Scosche 6 1/2" speakers that I received as a gift one year and were just gathering dust.
Aluminum. I cut pieces off an old aluminum "speed limit" sign for the face of the boombox and for the door to the electronics bay door. I originally used the amp from some computer speakers but it sounded terrible which left holes in the wood, so the aluminum helped hide the previous holes drilled into the face of the boombox once I switched to the Jensen amp.
For a carrying handle I used the top most part of a backrest off of an old, broken kitchen chair.
Wire of different gauges and lengths.
Butt-end connectors and spade connectors of various sizes.
Set of small hinges for the electronics/battery bay.
Rubber feet (4) for the boombox to sit on.
A dc toggle switch to power the amp and usb charger on and off.
Paint to give the boombox a little character.
An RCA to 1/8" headphone plug to connect my music to the amp.
Wood screws of different sizes as needed.
A 12V SLA rechargeable battery for the power source. As mentioned above I was fortunate to be given several 6V batteries, which when 2 were connected together made them 12V batteries.
I used polyfill from an old throw pillow to add into the speaker chambers to deepen the bass and improve the overall sound of the speakers.
Wood glue. Lots of wood glue! In this case I used Gorilla wood glue for a strong hold.
Silicone sealant to seal the speaker in it's chamber.
Bondo to cover the screws and any additional scratches and dings. Remember Bondo is sandable.

This list is just what I used for this build, not all these items were "needed" but I decided to try and do it semi-right. There are tons of different ways to make something like this as well as many, many different materials that can be used. I suggest being creative and using what you might have on hand. Also, I know there are chip amp kits out there that are efficient energy-wise, but as I didn't have one handy I wasn't about to buy one. If that were the case I would have just bought an MP3 boombox from the big box stores instead of building one.

Step 2: Tools Needed.

There are several tools you will definitely need :

A saw - electric or a hand saw to cut the plywood. A jig saw would work just as well as you will need to cut the holes in which to mount your speakers.
A drill or screw drivers -to drive any screws you use.
A sander of some sort - whether electric or hand powered this is great to smooth out the plywood and any rough edges.
A chisel - to counter sink the aluminum face on the front of the boombox and counter sink the electronics/battery bay access door on the back.
A crimper - to crimp the butt-end connectors and the spade connectors to the wire being used.
A hack saw - to cut the aluminum.
A file - to smooth out any rough edges on the aluminum.

There are probably a myriad of other tools you can use to help you complete a similar build better, faster, and safer. The above basic tools got me through this build.

Step 3: Lay Out the Measurements.

Once I had my design in mind I laid them out on the plywood I would be using. Again, I didn't take any pics of the first few stages of the build so I apologize. I checked my measurements twice, even three times before doing any actual cutting or drilling. Once I had all ten (10) pieces cut I sanded them to get ready to actually put together. I then commenced to put the box together. Wanting the speakers separate from the electronics I opted to cut and install two dividers before putting on the back panel. I was very liberal with the glue and the screws. I then came behind and used regular Bondo (which is sandable) to cover all the screws. Once put together I went on to the painting part of the build. My kids and I had lots of fun doing this part; in fact I think this was the funnest but longest part of the build. The NINERS and the SPURS emblems are in fact painted on and are not stickers or decals. Once painted the amp, speakers, USB charger, and the toggle switch were added. Then finally the rubber feet underneath.

Step 4: Turn Up the Music and Enjoy Yourself at the Pool/beach/bar-b-que !

At 22 1/2" l X 8 1/2" w X 8" h this boombox is not too bulky nor is it very heavy. This boombox has been enjoyed by the pool, at the beach, and at several 'ques. I have not had any problems with over heating. While heated some, especially during the summer, the amp has held up pretty good. The battery has lasted well over nine (9) hours at moderate to loud volumes with the amp input turned to full max. NOT once have I had the battery die or get so low as to make the amp start clipping out, despite having two (2) batteries on stand by. I hope this build and all the other builds like this one out there inspire you to build your own regardless of how it looks, what materials are used, or how it sounds. Thank you!