MOTM

For those discussing ribbon controllers DIY, I found these excerpts on the
web; hope this helps:


"There is information on building a ribbon controller in "Electronic Music
Circuits" by B. Klein. This one is basically a rheostat using a long strip
of conductive foam such as you find protecting semiconductors from static
charges. The foam is placed on non-conductive material (wood, etc.) and two
metal plates are attached at each end. One plate is connected to ground and
the other to a +15V supply. Now, at a slight distance above the foam you
place a piece of metallized mylar film that leads to the Control Voltage out
jack. When you press on the mylar film it makes contact with the foam
somewhere between 0 and 15V. As you slide your finger along the film, the
voltage changes."


"I added a 2-foot long ribbon controller just above the keyboard, with a
range of about +/- 5 octaves. I used black rubberized anti-static bag
material for the resistive element, and a steel band about 1/4" wide for the
ribbon. I mounted a separate linear power supply inside the case so as not
to disturb the existing circuitry. The ribbon is buffered by a TL-082 which
simply goes straight to all 16 VCO's via a 100K 1% resistor added to each
VCO's summing node. There is no memory S/H cap, so the pitch is only
affected when you press on the ribbon. Autotune still works, as long as you
leave the ribbon alone during the tuning process. Now I can do CS-80 bends
and get the VCO's down to a couple of hertz."


"There are several [vendors for the resistive vinyl element], but one that I
know from the top of my head is http://www.interlinkelec.com/ I don't know
their current line up, but they are company we used back in the Oberheim
days.--Tony Karavidas, Encore Electronics"

I haven't tried this myself, but how about using magnetic tape for a 
ribbon.  You could stretch it just above a metal surface.  I would 
think that tape would have a fairly linear resistance over a 
length.  You could use 1/2" or 1" rather than 1/4" and use the 
thicker, sturdier grade.  It's readily available.  
Just an idea.
BTW, you can also do interesting things with that conductive foam 
stuff that Paul sends us his ICs in.  The resistance of the foam 
varies with the pressure applied to it.  Back in the 70s I added 
pressure sensitivity to a Moog keyboard using this stuff.