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
https://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.
Step 2: Holes
Step 3: Wires
Strip off an inch of the plastic casing at the top
Feed one through the hole in one half and the other in the other half
Step 4: Soldering
Step 5: Finishing Off
Step 6: Velcro
Then with the furry sides glue to the tennis ball where the two halfs meet. Look at picture if you need more help.
Do this on two section of the tennis ball one on the opposite side to the other.
Step 7: Amp
Firstly mark out were you will need to put holes for the buttons and switches. Then carefully cut them make holes in the box with a pencil or something. Slide in the circuit board making sure that all buttons are carefully aligned. Glue the board to the box so the board does not slide about.
Step 8: Battery
Close up the box.
And try it.
Any constructive criticism welcome. : )