Use your Phillips screwdriver to remove all screws from the front and back of your computer or stereo speaker. Then pull the front grill (mesh cover) off of the front of the speaker and use your fingers to open up the speaker at its seams and expose the internal components. Consult the speaker's user guide if you are having trouble figuring out how the pieces connect.
Use your screwdriver to remove all screws from the actual speaker assembly and then place the speaker in your storage box so the speaker cable is draped over the side. The storage box shouldn't be any larger than 2 feet by 2 feet.
Drill a hole in the middle of your PVC end cap 1/2 inch in diameter. Make sure your PVC end cap is just big enough to cover the speaker. Fit the end cap over the speaker.
Place one end of your tubing (about 5 feet in length) in the hole in the end cap. Do not stick it down too far as you do not want the tubing to touch the actual speaker.
Wrap duct tape around the base of the tube where you stuck it in. Wrap it well, as you want it to be airtight and secure.
Plug the speakers into your amplifier and place the end of the tube in your mouth. As you talk into the tube you words will be distorted through the talk box you just made.