Joel Laird completed a fine PhD thesis on physical modelling drums in 2001, which included C++ sourcecode for an accurate model of a drum and a felt mallet for hitting it with. I’ve been in contact with Joel and am very happy to have prompted him to license the source under the GPL.
A .tar.gz file including some windows demo programs and the (Borland) C++ source is here. I hope to make some time to translate some of it into realtime supercollider unit generators soon…
I ported it to GNU C++, a version with my edits is available here.