Bend/hack an old ball mouse to make it do lots of sounds as you move it.

Step 4: Finishing touches.

Weld the presets to the negative pin of both sensors before sending the signal out to set amplitude of the signals.
Check that everything is as the veery simple circuit drawing.
Glue the presets on the board where you want. Out of the mechanical way of the disk, ball, etc.

Now just weld the + and - of the signal to the external audio cable.
Glue everything in place. The LEDS cables under the board, the board and any cable that is loose.
For the last, weld the audio jack at the end of the audio cable.
If you use the 9v battery, weld a plug for it and glue the battery on the mouse.
If you you use a switching DC converter, weld + and - to the thin cables.
Reassamble and its done!

Plug and Play!