These are very easy to make, it took me 15 minutes on my first ones.
WHAT YOU NEED;
9v battery clip
a tennis ball
An amp taken out of computer speakers
http://www.instructables.com/id/Super-easy-to-make-portable-speakers-for-mp3ipod ( look at this for how get a small amp. The smaller the better)
Small box to fit in your small amp
an old set of headphones
2 speakers with a diameter of no more than 5 and a half centimeters
10 cm of velcro
Lets get started............................
Step 1: Open the tennis ball
Than take something such as a pen knife or stanley knife and carefully cut the tennis ball open.
You then have two halves of a tennis ball.