I found this tutorial explaining very basicly how a multi touch works and how to build one.
Later that day, I saw these videos and I thought it was a bit weird, but maybe I could do something with it.

I came up with the idea of builing the multitouch box and then hooking this up in the way they do to 'bend' circuits so that the X and Y coordinates detected on the touch screen change parametres of the sound, whether it's a filter frequency or LFO rate. I figured maybe it'd be possible to have an on-screen keyboard at the bottom of the touch screen as well or even get a simple toy keyboard, change the oscillators and resistance on that.

At the moment, this is just a thought and I was hoping some of the more electronic-savvy of you would be able to tell me if this would be possible or if it's just too idealistic.
I'm also working on a very low budget but I've read that each part of this is relatively cheap and I can always resort to eBay and/or my dad's lab for parts.