Ctrlr is a free opensource project where they build vst plugin editors for hardware synths.
The skin I have made is for the Yamaha TX81-Z Synthesizer and is called 'TX81ZLime', it can be downloaded here
ofcourse you need the hardware synthesizer aswell for this to work.
Updated version for Ctrlr version 5 can be downloaded here.
Screenshot (not in use) may look abit different in your host.