OWLSim is a Juce-based software framework where effects patches can be compiled into VST and Audiounit plugins. We recommend compiling VST only as a preference, as compiling Audiounits requires adding extra Core Audio files and can be tricky to set up.
For step-by-step instructions, visit the Getting Started page.
Mac OS X VST: OwlSim-osx-vst-0.2
(unzip and copy OwlSim.vst to ~/Library/Audio/Plug-Ins/VST/)
Source code from github