You can play around with a lot of this stuff in the ChucK programming language[1]. ChucK was co-created by one of the early advocates for physical modeling sound synthesis, of which Karplus-Strong is an instance. A few examples are in [2] [3] and [4]. Disclosure: I am one of the current developers working on ChucK.
Awesome work, I really love ChucK and participated in the mailing list at some point to work out how to embed ChucK into another app. Conclusion: it wasn't easy as the code has a lot of global static state but I had ChucK as the audio solution for a game I never finished.
Nice! If you ever are working on something like that in the future, I am working on libchuck[1] which should make embedding easier, in spite of pervasive global state. Currently iOS/Mac only but plans are in the works to make it cross platform.
[1] http://chuck.stanford.edu/
[2] http://chuck.stanford.edu/doc/examples/deep/plu.ck
[3] http://chuck.stanford.edu/doc/examples/deep/plu2.ck
[3] http://chuck.stanford.edu/doc/examples/deep/plu3.ck