I've just built the prototype of the Repatcher-Extended, an Arduino patchbay matrix controller for Pure Data patches. It is based on the rePatcher by Open Music Labs (http://www.openmusiclabs.com/projects/repatcher/), extending it with shift registers and multiplexers. You can check a demo video here
You can get the code here http://drymonitis.me/code/
or here http://patchingcircleathens.labyrinthos.gr/projects/modular-synth/