What you will need is:
A briefcase (or something hard to screw a speaker into)
Old computer speakers that have a 9 volt input
A speaker (I used a 6x9 car speaker)
Small bolts and nuts
A 9 volt battery attachment from radioshack
A dremel tool or drill
Take the computer speaker apart. What you are trying to get out is the computer part that connects to its speaker. Detach from the speaker. Strip the wire and take the plug off.
Attach the 9 volt battery to the power point on the old computer speaker insides. make sure to twist this on pretty good otherwise it could come loose.
Attach the wire that was attached to your computer speaker to the new speaker. Turn on the speaker (because you left the power button and volume control on the old speaker) and test to see if it turns on. I left my light on there so when it turns on the light goes on. Now test to see it music comes though by attaching an ipod or something. Great - it works!
Take the speaker and make an outline with a pencil. Take your dremel tool or drill and drill a bunch of holes. Then attach your speaker with nuts and bolts.
There you go! A lot of people have thought this is pretty cool. It's a whole lot louder than you would think. Bring an extra 9 volt battery. It will last 4-6 hours continuous because you're putting a lot of power into a big speaker with a small battery.