I wasn't able to work on the hardware aspects of the project in the past few weeks, but I was able to work on the software. This lead to me uncovering more ways to interact with the cores. Check out the video demo here:

I'm going to take another run at the active stylus concept to see if I can influence the sense wire with more zest. I took apart an old relay, and that coil should do the trick. After that I won't pursue the active stylus any more because I have a better software solution in mind to get the same effect. It will maintain the benefit of a passive stylus, but still get me the full drawing capability that I was going after.