Step 1: Backstory
above are pictures of the previous amp and speakers I used. the amp came out of an HMDX hangtime Bluetooth speaker and I would highly recommend using it as it had great quality and was very loud. the only reason I wasn't using it is because towards the end of its life the charging port snapped off so I had to add a whole other amp just to charge the battery. the speaker I don't know anything about. it came from my cousin and it had very good sound. Im not using it because I made the very bad mistake of using hot glue and when I dropped the "indestructable ammo can speaker" the hot glue that was on the speaker itself ripped the speaker. more about that later.
Step 2: Materials
ammo can of your choice. I used a .30 cal ammo can because I wanted it more portable. get them surplus there a lot cheaper. you could probably fit 2 4" speakers in a .50 cal ammo can.
4" speakers of your choice. I got the cheapest ones I could find ($12 for two!) but I would spend a little more for higher quality if I could. mine are the boss extreme 4" 8ohm speakers from amazon.
any small Bluetooth speaker. I don't even know what kind mine is. you don't have to spend more than $25 to get a decent one as long as its loud, connects to your phone, and sounds good it will work. every Bluetooth speaker is diffrent so choose one that is easy to use.
your miscellaneous circuitry tools. soldering iron and solder (altho you could tie the wires together and bootleg it but solder is a lot better.) wire cutters, wire etc.