So i needed some portable sound system to take to the beach. Since stuff like that is quite expensive, i thought why not to make something my self. I knew that it should be super light weight, cause i dont want to drag around anything more than i really need to :) since beach is very public space, i thought i do not need it to be super loud, cause annoying people around me is not my intentions. SO this is what i came up with :) sorry, for the very vague instructable. this is my first one, and i built it like a year ago.Also i lost some of the pictures f.e mpr modules before it was instaled in the case.
since i am making something new now i decided to share this one :) constructive criticism and comments are welcome :)
You will need:
Empty metal whisky box (free)
speakers (i used my old creative 2.1 system speakers. for me they wore free. I guess u can pick them up cheap or almost for free if the sub is broken)
mp3 module (~5$)
3.7 lion Rechargeble Battery (~1.5 depending on the capacity, mine was 4000 mAh)
battery holder (no more than 1$)
Liquid rubber. (3$ in my country at least)
Rubber glue (most of people have this stuff at home not sure for the price)
Patting for the boombox (was in the speakers i had)
Some wires
Heat shrink if u want or some electrical tape will do
solder
Tools:
scissors
Dremel
soldering iron.

Step 1: Speakers

first you need to take apart the speakers from their original enclosure. And save the needed parts. Such as a plastic rings, speakers them selves, bolts and patting :) After you have to measure if they will fit in your whisky box. If not either find a bigger whisky box or smaller speakers. Box should be deep and wide enough. If you think that they will fit, make a pilot hole for the speaker anyway. Just to be sure.

Step 2: Cutting Holes

Next you have to cut the holes (in case you already did pilot hole, for you just hole) for speakers, and the mp3 module. I placed my mp3 module on the stop. So the branding of the box be visible and more esthetically pleasing. Since i didnt had needed dremel heads for cutting i just used scissors for making my holes. Not the best solution, but since the metal is very thin and edges will be covered up by the speakers and the mp3 module front panel, i didnt really was a big deal. I sugest to use something more sophisticated :D but if u dont, than not a big deal. But i strongly recommend to file edges so you do not cut your self in the assembly process :)

Step 3: Preparing the Enclosure

Well as you might suspect, metal box is not the ideal, or really suitable enclosure for sound system by it self. If you would assemble everything right now, and did the sound check, well it would sound like it is coming from the metal box. Sound is not pleasurable, believe me. To avoid this, and also prevent from standing waves forming and unwanted resonance i sprayed inside of my box with the liquid rubber. It worked like magic. Also putting some patting is needed :) but that in the later steps :) do not forget to mask outside of the box with masking tape. That stuff sticks really good really fast.

Step 4: Wiring and Finishing Up

So after the rubber dries you just have to wire speakers and the battery to the mp3 module. Before i used and old phone to power my module. Since it needs 3.7 V, and most old mobile phones have exact voltage on thei batteries. But after some time i bought lion 3.7 4000 mAh. It just lasts like 10 times longer this way :) after just put eveything into places. I used rubber glue, to seal the speakers and the mp3 module in place, so they wont be leaking sound. small hole was left in the mp3 player due to the fact that IR transmiter was built in very strange place :) After just pop the box together and you are done :)

Step 5: Final Thoughts

So, it sounds nice, lightweight and with the 4000 mAh it last a long time. Since the speakers are only 3W so there was no need for a external amplifier. The in mine mp3 module worked just fine. On the downside bass is not that grate, but it there is some kick to it. Sound is clear and is loud enough to enjoy music in the beach with your friends. If i have to make the project again, i also would incorporate charging schematic and you could charge it from the wall outlet :) also. The IR transmiter is on the top so you have to use remote control directly above the boombox. I didint think about that while i was making it. Sure i could just desolder the transmiter from the board and place it somewhere else, but it is like a first born child :) i'll just let it be and maybe come back one day with the upgraded version :) so let me know what you think. And i hope that instructable was not terrible to follow :)