mtf - instrument design

I've had minimal luck with toys. They've been too limited, and a couple are now too busted.
As such I propose to bend a cassette walkman.
Creating a new device - The Wobbly Man... or something like that :)

By changing the voltage to the motor I can change the playback speed/pitch, and even reverse direction of the tape.

This will be controlled/played by either a) a pot, controlling the variable voltage ouput of a regulator
and/or b) the thick pencil line on a piece of paper controlling variable resistance.

I will have multiple tapes each with unique sonic characteristics giving an array of potential playback timbres.

The instrument will consist of the walkman itself, a voltage regulator as created (or attempted) in week 5, and a pencil and a piece of paper.
I have yet to discover exactly how to integrate the pencil and piece of paper.

As for packaging, I plan to mount it inside a clear plastic drink bottle - giving the needed rigidity for such things as patch leads and also a lovely view of exposed wires.