Controller module allows you to design a custom “front panel” user interface for a patch. When the patch is opened in miRack AUv3 plugin, the designed panel will be shown, hiding the rest of the patch. Now you can create effect or instrument patches having all the power of miRack modules under the hood but hiding their complexity behind a custom user interface.
Below is an example of what a custom UI for a patch may look like inside an AUv3 host app:
Controller can as well be used in standalone miRack if you want to have a quick access to a set of parameters in one place. And in the future, you will be able to add custom modules created using Controller to other patches just like regular ones.